diff --git a/Src/Notion.Client/Api/Blocks/BlocksClient.cs b/Src/Notion.Client/Api/Blocks/BlocksClient.cs
index 4c038cc5..cc06642e 100644
--- a/Src/Notion.Client/Api/Blocks/BlocksClient.cs
+++ b/Src/Notion.Client/Api/Blocks/BlocksClient.cs
@@ -14,7 +14,7 @@ public BlocksClient(IRestClient client)
             _client = client;
         }
 
-        public async Task<PaginatedList<Block>> RetrieveChildrenAsync(string blockId, BlocksRetrieveChildrenParameters parameters = null)
+        public async Task<PaginatedList<IBlock>> RetrieveChildrenAsync(string blockId, BlocksRetrieveChildrenParameters parameters = null)
         {
             if (string.IsNullOrWhiteSpace(blockId))
             {
@@ -31,10 +31,10 @@ public async Task<PaginatedList<Block>> RetrieveChildrenAsync(string blockId, Bl
                 { "page_size", queryParameters?.PageSize?.ToString() }
             };
 
-            return await _client.GetAsync<PaginatedList<Block>>(url, queryParams);
+            return await _client.GetAsync<PaginatedList<IBlock>>(url, queryParams);
         }
 
-        public async Task<PaginatedList<Block>> AppendChildrenAsync(string blockId, BlocksAppendChildrenParameters parameters = null)
+        public async Task<PaginatedList<IBlock>> AppendChildrenAsync(string blockId, BlocksAppendChildrenParameters parameters = null)
         {
             if (string.IsNullOrWhiteSpace(blockId))
             {
@@ -45,10 +45,10 @@ public async Task<PaginatedList<Block>> AppendChildrenAsync(string blockId, Bloc
 
             var body = (IBlocksAppendChildrenBodyParameters)parameters;
 
-            return await _client.PatchAsync<PaginatedList<Block>>(url, body);
+            return await _client.PatchAsync<PaginatedList<IBlock>>(url, body);
         }
 
-        public async Task<Block> RetrieveAsync(string blockId)
+        public async Task<IBlock> RetrieveAsync(string blockId)
         {
             if (string.IsNullOrWhiteSpace(blockId))
             {
@@ -57,10 +57,10 @@ public async Task<Block> RetrieveAsync(string blockId)
 
             var url = BlocksApiUrls.Retrieve(blockId);
 
-            return await _client.GetAsync<Block>(url);
+            return await _client.GetAsync<IBlock>(url);
         }
 
-        public async Task<Block> UpdateAsync(string blockId, IUpdateBlock updateBlock)
+        public async Task<IBlock> UpdateAsync(string blockId, IUpdateBlock updateBlock)
         {
             if (string.IsNullOrWhiteSpace(blockId))
             {
@@ -69,7 +69,7 @@ public async Task<Block> UpdateAsync(string blockId, IUpdateBlock updateBlock)
 
             var url = BlocksApiUrls.Update(blockId);
 
-            return await _client.PatchAsync<Block>(url, updateBlock);
+            return await _client.PatchAsync<IBlock>(url, updateBlock);
         }
 
         public async Task DeleteAsync(string blockId)
diff --git a/Src/Notion.Client/Api/Blocks/IBlocksClient.cs b/Src/Notion.Client/Api/Blocks/IBlocksClient.cs
index 4c088803..90ebf073 100644
--- a/Src/Notion.Client/Api/Blocks/IBlocksClient.cs
+++ b/Src/Notion.Client/Api/Blocks/IBlocksClient.cs
@@ -9,7 +9,7 @@ public interface IBlocksClient
         /// </summary>
         /// <param name="blockId"></param>
         /// <returns>Block</returns>
-        Task<Block> RetrieveAsync(string blockId);
+        Task<IBlock> RetrieveAsync(string blockId);
 
         /// <summary>
         /// Updates the content for the specified block_id based on the block type.
@@ -17,9 +17,9 @@ public interface IBlocksClient
         /// <param name="blockId"></param>
         /// <param name="updateBlock"></param>
         /// <returns>Block</returns>
-        Task<Block> UpdateAsync(string blockId, IUpdateBlock updateBlock);
+        Task<IBlock> UpdateAsync(string blockId, IUpdateBlock updateBlock);
 
-        Task<PaginatedList<Block>> RetrieveChildrenAsync(string blockId, BlocksRetrieveChildrenParameters parameters = null);
+        Task<PaginatedList<IBlock>> RetrieveChildrenAsync(string blockId, BlocksRetrieveChildrenParameters parameters = null);
 
         /// <summary>
         /// Creates and appends new children blocks to the parent block_id specified.
@@ -27,7 +27,7 @@ public interface IBlocksClient
         /// <param name="blockId">Identifier for a block</param>
         /// <param name="parameters"></param>
         /// <returns>A paginated list of newly created first level children block objects.</returns>
-        Task<PaginatedList<Block>> AppendChildrenAsync(string blockId, BlocksAppendChildrenParameters parameters = null);
+        Task<PaginatedList<IBlock>> AppendChildrenAsync(string blockId, BlocksAppendChildrenParameters parameters = null);
 
         /// <summary>
         /// Sets a Block object, including page blocks, to archived: true using the ID specified.
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksAppendChildrenParameters.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksAppendChildrenParameters.cs
index a2ad3440..e78899bb 100644
--- a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksAppendChildrenParameters.cs
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksAppendChildrenParameters.cs
@@ -4,6 +4,6 @@ namespace Notion.Client
 {
     public class BlocksAppendChildrenParameters : IBlocksAppendChildrenBodyParameters
     {
-        public IEnumerable<Block> Children { get; set; }
+        public IEnumerable<IBlock> Children { get; set; }
     }
 }
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/IBlocksAppendChildrenBodyParameters.cs b/Src/Notion.Client/Api/Blocks/RequestParams/IBlocksAppendChildrenBodyParameters.cs
index 33b0ca0f..bdd4d324 100644
--- a/Src/Notion.Client/Api/Blocks/RequestParams/IBlocksAppendChildrenBodyParameters.cs
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/IBlocksAppendChildrenBodyParameters.cs
@@ -7,6 +7,6 @@ namespace Notion.Client
     public interface IBlocksAppendChildrenBodyParameters
     {
         [JsonProperty("children")]
-        IEnumerable<Block> Children { get; set; }
+        IEnumerable<IBlock> Children { get; set; }
     }
 }
diff --git a/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/IPagesCreateBodyParameters.cs b/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/IPagesCreateBodyParameters.cs
index 7e275bfc..9b9f0631 100644
--- a/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/IPagesCreateBodyParameters.cs
+++ b/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/IPagesCreateBodyParameters.cs
@@ -12,7 +12,7 @@ public interface IPagesCreateBodyParameters
         IDictionary<string, PropertyValue> Properties { get; set; }
 
         [JsonProperty("children")]
-        IList<Block> Children { get; set; }
+        IList<IBlock> Children { get; set; }
 
         [JsonProperty("icon")]
         IPageIcon Icon { get; set; }
diff --git a/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/PagesCreateParameters.cs b/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/PagesCreateParameters.cs
index 49b8f44d..52cb0a89 100644
--- a/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/PagesCreateParameters.cs
+++ b/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/PagesCreateParameters.cs
@@ -6,7 +6,7 @@ public class PagesCreateParameters : IPagesCreateBodyParameters, IPagesCreateQue
     {
         public IPageParentInput Parent { get; set; }
         public IDictionary<string, PropertyValue> Properties { get; set; }
-        public IList<Block> Children { get; set; }
+        public IList<IBlock> Children { get; set; }
         public IPageIcon Icon { get; set; }
         public FileObject Cover { get; set; }
     }
diff --git a/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/PagesCreateParametersBuilder.cs b/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/PagesCreateParametersBuilder.cs
index 02e5b57b..b86a207a 100644
--- a/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/PagesCreateParametersBuilder.cs
+++ b/Src/Notion.Client/Api/Pages/RequestParams/PagesCreateParameters/PagesCreateParametersBuilder.cs
@@ -6,7 +6,7 @@ public class PagesCreateParametersBuilder
     {
         private IPageParentInput parent;
         private readonly Dictionary<string, PropertyValue> properties = new Dictionary<string, PropertyValue>();
-        private readonly IList<Block> children = new List<Block>();
+        private readonly IList<IBlock> children = new List<IBlock>();
         private IPageIcon icon;
         private FileObject cover;
 
@@ -28,7 +28,7 @@ public PagesCreateParametersBuilder AddProperty(string nameOrId, PropertyValue v
             return this;
         }
 
-        public PagesCreateParametersBuilder AddPageContent(Block block)
+        public PagesCreateParametersBuilder AddPageContent(IBlock block)
         {
             children.Add(block);
             return this;
diff --git a/Src/Notion.Client/Models/Blocks/AudioBlock.cs b/Src/Notion.Client/Models/Blocks/AudioBlock.cs
index b43bbc9c..040f346b 100644
--- a/Src/Notion.Client/Models/Blocks/AudioBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/AudioBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class AudioBlock : Block
+    public class AudioBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Audio;
 
diff --git a/Src/Notion.Client/Models/Blocks/Block.cs b/Src/Notion.Client/Models/Blocks/Block.cs
index c0687860..9ba90612 100644
--- a/Src/Notion.Client/Models/Blocks/Block.cs
+++ b/Src/Notion.Client/Models/Blocks/Block.cs
@@ -1,50 +1,17 @@
-using JsonSubTypes;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Converters;
-
-namespace Notion.Client
+namespace Notion.Client
 {
-    [JsonConverter(typeof(JsonSubtypes), "type")]
-    [JsonSubtypes.KnownSubType(typeof(AudioBlock), BlockType.Audio)]
-    [JsonSubtypes.KnownSubType(typeof(BookmarkBlock), BlockType.Bookmark)]
-    [JsonSubtypes.KnownSubType(typeof(BulletedListItemBlock), BlockType.BulletedListItem)]
-    [JsonSubtypes.KnownSubType(typeof(CalloutBlock), BlockType.Callout)]
-    [JsonSubtypes.KnownSubType(typeof(ChildPageBlock), BlockType.ChildPage)]
-    [JsonSubtypes.KnownSubType(typeof(ChildDatabaseBlock), BlockType.ChildDatabase)]
-    [JsonSubtypes.KnownSubType(typeof(CodeBlock), BlockType.Code)]
-    [JsonSubtypes.KnownSubType(typeof(DividerBlock), BlockType.Divider)]
-    [JsonSubtypes.KnownSubType(typeof(EmbedBlock), BlockType.Embed)]
-    [JsonSubtypes.KnownSubType(typeof(EquationBlock), BlockType.Equation)]
-    [JsonSubtypes.KnownSubType(typeof(FileBlock), BlockType.File)]
-    [JsonSubtypes.KnownSubType(typeof(HeadingOneBlock), BlockType.Heading_1)]
-    [JsonSubtypes.KnownSubType(typeof(HeadingTwoBlock), BlockType.Heading_2)]
-    [JsonSubtypes.KnownSubType(typeof(HeadingThreeeBlock), BlockType.Heading_3)]
-    [JsonSubtypes.KnownSubType(typeof(ImageBlock), BlockType.Image)]
-    [JsonSubtypes.KnownSubType(typeof(NumberedListItemBlock), BlockType.NumberedListItem)]
-    [JsonSubtypes.KnownSubType(typeof(ParagraphBlock), BlockType.Paragraph)]
-    [JsonSubtypes.KnownSubType(typeof(PDFBlock), BlockType.PDF)]
-    [JsonSubtypes.KnownSubType(typeof(QuoteBlock), BlockType.Quote)]
-    [JsonSubtypes.KnownSubType(typeof(TableOfContentsBlock), BlockType.TableOfContents)]
-    [JsonSubtypes.KnownSubType(typeof(ToDoBlock), BlockType.ToDo)]
-    [JsonSubtypes.KnownSubType(typeof(ToggleBlock), BlockType.Toggle)]
-    [JsonSubtypes.KnownSubType(typeof(VideoBlock), BlockType.Video)]
-    [JsonSubtypes.KnownSubType(typeof(UnsupportedBlock), BlockType.Unsupported)]
-    public class Block : IObject
+    public abstract class Block : IBlock
     {
         public ObjectType Object => ObjectType.Block;
+
         public string Id { get; set; }
 
-        [JsonProperty("type")]
-        [JsonConverter(typeof(StringEnumConverter))]
         public virtual BlockType Type { get; set; }
 
-        [JsonProperty("created_time")]
         public string CreatedTime { get; set; }
 
-        [JsonProperty("last_edited_time")]
         public string LastEditedTime { get; set; }
 
-        [JsonProperty("has_children")]
         public virtual bool HasChildren { get; set; }
     }
 }
diff --git a/Src/Notion.Client/Models/Blocks/BlockType.cs b/Src/Notion.Client/Models/Blocks/BlockType.cs
index 1c353686..b46e6c9a 100644
--- a/Src/Notion.Client/Models/Blocks/BlockType.cs
+++ b/Src/Notion.Client/Models/Blocks/BlockType.cs
@@ -76,6 +76,12 @@ public enum BlockType
         [EnumMember(Value = "quote")]
         Quote,
 
+        [EnumMember(Value = "column")]
+        Column,
+
+        [EnumMember(Value = "column_list")]
+        ColumnList,
+
         [EnumMember(Value = "unsupported")]
         Unsupported
     }
diff --git a/Src/Notion.Client/Models/Blocks/BookmarkBlock.cs b/Src/Notion.Client/Models/Blocks/BookmarkBlock.cs
index c0380b73..735b1725 100644
--- a/Src/Notion.Client/Models/Blocks/BookmarkBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/BookmarkBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class BookmarkBlock : Block
+    public class BookmarkBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Bookmark;
 
diff --git a/Src/Notion.Client/Models/Blocks/BreadcrumbBlock.cs b/Src/Notion.Client/Models/Blocks/BreadcrumbBlock.cs
index 197122bc..73ae614d 100644
--- a/Src/Notion.Client/Models/Blocks/BreadcrumbBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/BreadcrumbBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class BreadcrumbBlock : Block
+    public class BreadcrumbBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Breadcrumb;
 
diff --git a/Src/Notion.Client/Models/Blocks/BulletedListItemBlock.cs b/Src/Notion.Client/Models/Blocks/BulletedListItemBlock.cs
index c787da86..15d168af 100644
--- a/Src/Notion.Client/Models/Blocks/BulletedListItemBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/BulletedListItemBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class BulletedListItemBlock : Block
+    public class BulletedListItemBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.BulletedListItem;
 
@@ -16,7 +16,7 @@ public class Info
             public IEnumerable<RichTextBase> Text { get; set; }
 
             [JsonProperty("children")]
-            public IEnumerable<Block> Children { get; set; }
+            public IEnumerable<INonColumnBlock> Children { get; set; }
         }
     }
 }
diff --git a/Src/Notion.Client/Models/Blocks/CalloutBlock.cs b/Src/Notion.Client/Models/Blocks/CalloutBlock.cs
index 7c355a21..9fed148a 100644
--- a/Src/Notion.Client/Models/Blocks/CalloutBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/CalloutBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class CalloutBlock : Block
+    public class CalloutBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Callout;
 
@@ -19,7 +19,7 @@ public class Info
             public IPageIcon Icon { get; set; }
 
             [JsonProperty("children")]
-            public IEnumerable<Block> Children { get; set; }
+            public IEnumerable<INonColumnBlock> Children { get; set; }
         }
     }
 }
diff --git a/Src/Notion.Client/Models/Blocks/ChildDatabaseBlock.cs b/Src/Notion.Client/Models/Blocks/ChildDatabaseBlock.cs
index eb4577b7..273836a9 100644
--- a/Src/Notion.Client/Models/Blocks/ChildDatabaseBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/ChildDatabaseBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class ChildDatabaseBlock : Block
+    public class ChildDatabaseBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.ChildDatabase;
 
diff --git a/Src/Notion.Client/Models/Blocks/ChildPageBlock.cs b/Src/Notion.Client/Models/Blocks/ChildPageBlock.cs
index 9fdc4b7b..91c8f343 100644
--- a/Src/Notion.Client/Models/Blocks/ChildPageBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/ChildPageBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class ChildPageBlock : Block
+    public class ChildPageBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.ChildPage;
 
diff --git a/Src/Notion.Client/Models/Blocks/CodeBlock.cs b/Src/Notion.Client/Models/Blocks/CodeBlock.cs
index 58ac5d6a..7eb4205d 100644
--- a/Src/Notion.Client/Models/Blocks/CodeBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/CodeBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class CodeBlock : Block
+    public class CodeBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Code;
 
diff --git a/Src/Notion.Client/Models/Blocks/ColumnBlock.cs b/Src/Notion.Client/Models/Blocks/ColumnBlock.cs
new file mode 100644
index 00000000..72cf2f3c
--- /dev/null
+++ b/Src/Notion.Client/Models/Blocks/ColumnBlock.cs
@@ -0,0 +1,19 @@
+using System.Collections.Generic;
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class ColumnBlock : Block
+    {
+        public override BlockType Type => BlockType.Column;
+
+        [JsonProperty("column")]
+        public Info Column { get; set; }
+
+        public class Info
+        {
+            [JsonProperty("children")]
+            public IEnumerable<IColumnChildrenBlock> Children { get; set; }
+        }
+    }
+}
diff --git a/Src/Notion.Client/Models/Blocks/ColumnListBlock.cs b/Src/Notion.Client/Models/Blocks/ColumnListBlock.cs
new file mode 100644
index 00000000..f86ecba0
--- /dev/null
+++ b/Src/Notion.Client/Models/Blocks/ColumnListBlock.cs
@@ -0,0 +1,19 @@
+using System.Collections.Generic;
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class ColumnListBlock : Block, INonColumnBlock
+    {
+        public override BlockType Type => BlockType.ColumnList;
+
+        [JsonProperty("column_list")]
+        public Info ColumnList { get; set; }
+
+        public class Info
+        {
+            [JsonProperty("children")]
+            public IEnumerable<ColumnBlock> Children { get; set; }
+        }
+    }
+}
diff --git a/Src/Notion.Client/Models/Blocks/DividerBlock.cs b/Src/Notion.Client/Models/Blocks/DividerBlock.cs
index 1b7bb447..61e0301b 100644
--- a/Src/Notion.Client/Models/Blocks/DividerBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/DividerBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class DividerBlock : Block
+    public class DividerBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Divider;
 
diff --git a/Src/Notion.Client/Models/Blocks/EmbedBlock.cs b/Src/Notion.Client/Models/Blocks/EmbedBlock.cs
index 5b3f715f..8332b683 100644
--- a/Src/Notion.Client/Models/Blocks/EmbedBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/EmbedBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class EmbedBlock : Block
+    public class EmbedBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Embed;
 
diff --git a/Src/Notion.Client/Models/Blocks/EquationBlock.cs b/Src/Notion.Client/Models/Blocks/EquationBlock.cs
index 79585539..310a76df 100644
--- a/Src/Notion.Client/Models/Blocks/EquationBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/EquationBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class EquationBlock : Block
+    public class EquationBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Equation;
 
diff --git a/Src/Notion.Client/Models/Blocks/FileBlock.cs b/Src/Notion.Client/Models/Blocks/FileBlock.cs
index c06533ed..5495e4bc 100644
--- a/Src/Notion.Client/Models/Blocks/FileBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/FileBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class FileBlock : Block
+    public class FileBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.File;
 
diff --git a/Src/Notion.Client/Models/Blocks/HeadingOneBlock.cs b/Src/Notion.Client/Models/Blocks/HeadingOneBlock.cs
index 2105cefe..d9c107c3 100644
--- a/Src/Notion.Client/Models/Blocks/HeadingOneBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/HeadingOneBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class HeadingOneBlock : Block
+    public class HeadingOneBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Heading_1;
 
diff --git a/Src/Notion.Client/Models/Blocks/HeadingThreeeBlock.cs b/Src/Notion.Client/Models/Blocks/HeadingThreeeBlock.cs
index 4f1ca0a0..0728f200 100644
--- a/Src/Notion.Client/Models/Blocks/HeadingThreeeBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/HeadingThreeeBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class HeadingThreeeBlock : Block
+    public class HeadingThreeeBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Heading_3;
 
diff --git a/Src/Notion.Client/Models/Blocks/HeadingTwoBlock.cs b/Src/Notion.Client/Models/Blocks/HeadingTwoBlock.cs
index 5b07e758..c9caec09 100644
--- a/Src/Notion.Client/Models/Blocks/HeadingTwoBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/HeadingTwoBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class HeadingTwoBlock : Block
+    public class HeadingTwoBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Heading_2;
 
diff --git a/Src/Notion.Client/Models/Blocks/IBlock.cs b/Src/Notion.Client/Models/Blocks/IBlock.cs
new file mode 100644
index 00000000..e36f371a
--- /dev/null
+++ b/Src/Notion.Client/Models/Blocks/IBlock.cs
@@ -0,0 +1,50 @@
+using JsonSubTypes;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Converters;
+
+namespace Notion.Client
+{
+    [JsonConverter(typeof(JsonSubtypes), "type")]
+    [JsonSubtypes.KnownSubType(typeof(AudioBlock), BlockType.Audio)]
+    [JsonSubtypes.KnownSubType(typeof(BookmarkBlock), BlockType.Bookmark)]
+    [JsonSubtypes.KnownSubType(typeof(BreadcrumbBlock), BlockType.Breadcrumb)]
+    [JsonSubtypes.KnownSubType(typeof(BulletedListItemBlock), BlockType.BulletedListItem)]
+    [JsonSubtypes.KnownSubType(typeof(CalloutBlock), BlockType.Callout)]
+    [JsonSubtypes.KnownSubType(typeof(ChildPageBlock), BlockType.ChildPage)]
+    [JsonSubtypes.KnownSubType(typeof(ChildDatabaseBlock), BlockType.ChildDatabase)]
+    [JsonSubtypes.KnownSubType(typeof(CodeBlock), BlockType.Code)]
+    [JsonSubtypes.KnownSubType(typeof(ColumnBlock), BlockType.Column)]
+    [JsonSubtypes.KnownSubType(typeof(ColumnListBlock), BlockType.ColumnList)]
+    [JsonSubtypes.KnownSubType(typeof(DividerBlock), BlockType.Divider)]
+    [JsonSubtypes.KnownSubType(typeof(EmbedBlock), BlockType.Embed)]
+    [JsonSubtypes.KnownSubType(typeof(EquationBlock), BlockType.Equation)]
+    [JsonSubtypes.KnownSubType(typeof(FileBlock), BlockType.File)]
+    [JsonSubtypes.KnownSubType(typeof(HeadingOneBlock), BlockType.Heading_1)]
+    [JsonSubtypes.KnownSubType(typeof(HeadingTwoBlock), BlockType.Heading_2)]
+    [JsonSubtypes.KnownSubType(typeof(HeadingThreeeBlock), BlockType.Heading_3)]
+    [JsonSubtypes.KnownSubType(typeof(ImageBlock), BlockType.Image)]
+    [JsonSubtypes.KnownSubType(typeof(NumberedListItemBlock), BlockType.NumberedListItem)]
+    [JsonSubtypes.KnownSubType(typeof(ParagraphBlock), BlockType.Paragraph)]
+    [JsonSubtypes.KnownSubType(typeof(PDFBlock), BlockType.PDF)]
+    [JsonSubtypes.KnownSubType(typeof(QuoteBlock), BlockType.Quote)]
+    [JsonSubtypes.KnownSubType(typeof(TableOfContentsBlock), BlockType.TableOfContents)]
+    [JsonSubtypes.KnownSubType(typeof(ToDoBlock), BlockType.ToDo)]
+    [JsonSubtypes.KnownSubType(typeof(ToggleBlock), BlockType.Toggle)]
+    [JsonSubtypes.KnownSubType(typeof(VideoBlock), BlockType.Video)]
+    [JsonSubtypes.KnownSubType(typeof(UnsupportedBlock), BlockType.Unsupported)]
+    public interface IBlock : IObject
+    {
+        [JsonProperty("type")]
+        [JsonConverter(typeof(StringEnumConverter))]
+        BlockType Type { get; set; }
+
+        [JsonProperty("created_time")]
+        string CreatedTime { get; set; }
+
+        [JsonProperty("last_edited_time")]
+        string LastEditedTime { get; set; }
+
+        [JsonProperty("has_children")]
+        bool HasChildren { get; set; }
+    }
+}
diff --git a/Src/Notion.Client/Models/Blocks/IColumnChildrenBlock.cs b/Src/Notion.Client/Models/Blocks/IColumnChildrenBlock.cs
new file mode 100644
index 00000000..9eaa5622
--- /dev/null
+++ b/Src/Notion.Client/Models/Blocks/IColumnChildrenBlock.cs
@@ -0,0 +1,66 @@
+using JsonSubTypes;
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    //[JsonConverter(typeof(JsonSubtypes), "type")]
+    //[JsonSubtypes.KnownSubType(typeof(AudioBlock), BlockType.Audio)]
+    //[JsonSubtypes.KnownSubType(typeof(BookmarkBlock), BlockType.Bookmark)]
+    //[JsonSubtypes.KnownSubType(typeof(BreadcrumbBlock), BlockType.Breadcrumb)]
+    //[JsonSubtypes.KnownSubType(typeof(BulletedListItemBlock), BlockType.BulletedListItem)]
+    //[JsonSubtypes.KnownSubType(typeof(CalloutBlock), BlockType.Callout)]
+    //[JsonSubtypes.KnownSubType(typeof(ChildDatabaseBlock), BlockType.ChildDatabase)]
+    //[JsonSubtypes.KnownSubType(typeof(ChildPageBlock), BlockType.ChildPage)]
+    //[JsonSubtypes.KnownSubType(typeof(CodeBlock), BlockType.Code)]
+    //[JsonSubtypes.KnownSubType(typeof(DividerBlock), BlockType.Divider)]
+    //[JsonSubtypes.KnownSubType(typeof(EmbedBlock), BlockType.Embed)]
+    //[JsonSubtypes.KnownSubType(typeof(EquationBlock), BlockType.Equation)]
+    //[JsonSubtypes.KnownSubType(typeof(FileBlock), BlockType.File)]
+    //[JsonSubtypes.KnownSubType(typeof(HeadingOneBlock), BlockType.Heading_1)]
+    //[JsonSubtypes.KnownSubType(typeof(HeadingTwoBlock), BlockType.Heading_2)]
+    //[JsonSubtypes.KnownSubType(typeof(HeadingThreeeBlock), BlockType.Heading_3)]
+    //[JsonSubtypes.KnownSubType(typeof(ImageBlock), BlockType.Image)]
+    //[JsonSubtypes.KnownSubType(typeof(NumberedListItemBlock), BlockType.NumberedListItem)]
+    //[JsonSubtypes.KnownSubType(typeof(ParagraphBlock), BlockType.Paragraph)]
+    //[JsonSubtypes.KnownSubType(typeof(PDFBlock), BlockType.PDF)]
+    //[JsonSubtypes.KnownSubType(typeof(QuoteBlock), BlockType.Quote)]
+    //[JsonSubtypes.KnownSubType(typeof(TableOfContentsBlock), BlockType.TableOfContents)]
+    //[JsonSubtypes.KnownSubType(typeof(ToDoBlock), BlockType.ToDo)]
+    //[JsonSubtypes.KnownSubType(typeof(ToggleBlock), BlockType.Toggle)]
+    //[JsonSubtypes.KnownSubType(typeof(VideoBlock), BlockType.Video)]
+    //[JsonSubtypes.KnownSubType(typeof(UnsupportedBlock), BlockType.Unsupported)]
+    public interface IColumnChildrenBlock : IBlock
+    {
+    }
+
+    //[JsonConverter(typeof(JsonSubtypes), "type")]
+    //[JsonSubtypes.KnownSubType(typeof(AudioBlock), BlockType.Audio)]
+    //[JsonSubtypes.KnownSubType(typeof(BookmarkBlock), BlockType.Bookmark)]
+    //[JsonSubtypes.KnownSubType(typeof(BreadcrumbBlock), BlockType.Breadcrumb)]
+    //[JsonSubtypes.KnownSubType(typeof(BulletedListItemBlock), BlockType.BulletedListItem)]
+    //[JsonSubtypes.KnownSubType(typeof(CalloutBlock), BlockType.Callout)]
+    //[JsonSubtypes.KnownSubType(typeof(ChildPageBlock), BlockType.ChildPage)]
+    //[JsonSubtypes.KnownSubType(typeof(ChildDatabaseBlock), BlockType.ChildDatabase)]
+    //[JsonSubtypes.KnownSubType(typeof(CodeBlock), BlockType.Code)]
+    //[JsonSubtypes.KnownSubType(typeof(ColumnListBlock), BlockType.ColumnList)]
+    //[JsonSubtypes.KnownSubType(typeof(DividerBlock), BlockType.Divider)]
+    //[JsonSubtypes.KnownSubType(typeof(EmbedBlock), BlockType.Embed)]
+    //[JsonSubtypes.KnownSubType(typeof(EquationBlock), BlockType.Equation)]
+    //[JsonSubtypes.KnownSubType(typeof(FileBlock), BlockType.File)]
+    //[JsonSubtypes.KnownSubType(typeof(HeadingOneBlock), BlockType.Heading_1)]
+    //[JsonSubtypes.KnownSubType(typeof(HeadingTwoBlock), BlockType.Heading_2)]
+    //[JsonSubtypes.KnownSubType(typeof(HeadingThreeeBlock), BlockType.Heading_3)]
+    //[JsonSubtypes.KnownSubType(typeof(ImageBlock), BlockType.Image)]
+    //[JsonSubtypes.KnownSubType(typeof(NumberedListItemBlock), BlockType.NumberedListItem)]
+    //[JsonSubtypes.KnownSubType(typeof(ParagraphBlock), BlockType.Paragraph)]
+    //[JsonSubtypes.KnownSubType(typeof(PDFBlock), BlockType.PDF)]
+    //[JsonSubtypes.KnownSubType(typeof(QuoteBlock), BlockType.Quote)]
+    //[JsonSubtypes.KnownSubType(typeof(TableOfContentsBlock), BlockType.TableOfContents)]
+    //[JsonSubtypes.KnownSubType(typeof(ToDoBlock), BlockType.ToDo)]
+    //[JsonSubtypes.KnownSubType(typeof(ToggleBlock), BlockType.Toggle)]
+    //[JsonSubtypes.KnownSubType(typeof(VideoBlock), BlockType.Video)]
+    //[JsonSubtypes.KnownSubType(typeof(UnsupportedBlock), BlockType.Unsupported)]
+    public interface INonColumnBlock : IBlock
+    {
+    }
+}
diff --git a/Src/Notion.Client/Models/Blocks/ImageBlock.cs b/Src/Notion.Client/Models/Blocks/ImageBlock.cs
index cead4547..17aa6bae 100644
--- a/Src/Notion.Client/Models/Blocks/ImageBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/ImageBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class ImageBlock : Block
+    public class ImageBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Image;
 
diff --git a/Src/Notion.Client/Models/Blocks/NumberedListItemBlock.cs b/Src/Notion.Client/Models/Blocks/NumberedListItemBlock.cs
index 3d233af3..90823f57 100644
--- a/Src/Notion.Client/Models/Blocks/NumberedListItemBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/NumberedListItemBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class NumberedListItemBlock : Block
+    public class NumberedListItemBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.NumberedListItem;
 
@@ -16,7 +16,7 @@ public class Info
             public IEnumerable<RichTextBase> Text { get; set; }
 
             [JsonProperty("children")]
-            public IEnumerable<Block> Children { get; set; }
+            public IEnumerable<INonColumnBlock> Children { get; set; }
         }
     }
 }
diff --git a/Src/Notion.Client/Models/Blocks/PDFBlock.cs b/Src/Notion.Client/Models/Blocks/PDFBlock.cs
index 84a3a29f..85458796 100644
--- a/Src/Notion.Client/Models/Blocks/PDFBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/PDFBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class PDFBlock : Block
+    public class PDFBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.PDF;
 
diff --git a/Src/Notion.Client/Models/Blocks/ParagraphBlock.cs b/Src/Notion.Client/Models/Blocks/ParagraphBlock.cs
index ebce97a7..4a0b5d07 100644
--- a/Src/Notion.Client/Models/Blocks/ParagraphBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/ParagraphBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class ParagraphBlock : Block
+    public class ParagraphBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Paragraph;
 
@@ -16,7 +16,7 @@ public class Info
             public IEnumerable<RichTextBase> Text { get; set; }
 
             [JsonProperty("children")]
-            public IEnumerable<Block> Children { get; set; }
+            public IEnumerable<INonColumnBlock> Children { get; set; }
         }
     }
 }
diff --git a/Src/Notion.Client/Models/Blocks/QuoteBlock.cs b/Src/Notion.Client/Models/Blocks/QuoteBlock.cs
index e7f6d829..3a4c6d9f 100644
--- a/Src/Notion.Client/Models/Blocks/QuoteBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/QuoteBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class QuoteBlock : Block
+    public class QuoteBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Quote;
 
@@ -16,7 +16,7 @@ public class Info
             public IEnumerable<RichTextBaseInput> Text { get; set; }
 
             [JsonProperty("children")]
-            public IEnumerable<Block> Children { get; set; }
+            public IEnumerable<INonColumnBlock> Children { get; set; }
         }
     }
 }
diff --git a/Src/Notion.Client/Models/Blocks/TableOfContentsBlock.cs b/Src/Notion.Client/Models/Blocks/TableOfContentsBlock.cs
index fe1e7b2e..49e11bf4 100644
--- a/Src/Notion.Client/Models/Blocks/TableOfContentsBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/TableOfContentsBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class TableOfContentsBlock : Block
+    public class TableOfContentsBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.TableOfContents;
 
diff --git a/Src/Notion.Client/Models/Blocks/ToDoBlock.cs b/Src/Notion.Client/Models/Blocks/ToDoBlock.cs
index da6518a2..2d033c95 100644
--- a/Src/Notion.Client/Models/Blocks/ToDoBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/ToDoBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class ToDoBlock : Block
+    public class ToDoBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.ToDo;
 
@@ -19,7 +19,7 @@ public class Info
             public bool IsChecked { get; set; }
 
             [JsonProperty("children")]
-            public IEnumerable<Block> Children { get; set; }
+            public IEnumerable<INonColumnBlock> Children { get; set; }
         }
     }
 }
diff --git a/Src/Notion.Client/Models/Blocks/ToggleBlock.cs b/Src/Notion.Client/Models/Blocks/ToggleBlock.cs
index 3da4d6d7..95eef646 100644
--- a/Src/Notion.Client/Models/Blocks/ToggleBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/ToggleBlock.cs
@@ -3,7 +3,7 @@
 
 namespace Notion.Client
 {
-    public class ToggleBlock : Block
+    public class ToggleBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Toggle;
 
@@ -16,7 +16,7 @@ public class Info
             public IEnumerable<RichTextBase> Text { get; set; }
 
             [JsonProperty("children")]
-            public IEnumerable<Block> Children { get; set; }
+            public IEnumerable<INonColumnBlock> Children { get; set; }
         }
     }
 }
diff --git a/Src/Notion.Client/Models/Blocks/UnsupportedBlock.cs b/Src/Notion.Client/Models/Blocks/UnsupportedBlock.cs
index b275813a..4164d550 100644
--- a/Src/Notion.Client/Models/Blocks/UnsupportedBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/UnsupportedBlock.cs
@@ -1,6 +1,6 @@
 namespace Notion.Client
 {
-    public class UnsupportedBlock : Block
+    public class UnsupportedBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Unsupported;
     }
diff --git a/Src/Notion.Client/Models/Blocks/VideoBlock.cs b/Src/Notion.Client/Models/Blocks/VideoBlock.cs
index 49a1a697..015bed96 100644
--- a/Src/Notion.Client/Models/Blocks/VideoBlock.cs
+++ b/Src/Notion.Client/Models/Blocks/VideoBlock.cs
@@ -2,7 +2,7 @@
 
 namespace Notion.Client
 {
-    public class VideoBlock : Block
+    public class VideoBlock : Block, IColumnChildrenBlock, INonColumnBlock
     {
         public override BlockType Type => BlockType.Video;
 
diff --git a/Src/Notion.Client/Models/IObject.cs b/Src/Notion.Client/Models/IObject.cs
index 98f50f3f..2f72f929 100644
--- a/Src/Notion.Client/Models/IObject.cs
+++ b/Src/Notion.Client/Models/IObject.cs
@@ -7,7 +7,7 @@ namespace Notion.Client
     [JsonConverter(typeof(JsonSubtypes), "object")]
     [JsonSubtypes.KnownSubType(typeof(Page), ObjectType.Page)]
     [JsonSubtypes.KnownSubType(typeof(Database), ObjectType.Database)]
-    [JsonSubtypes.KnownSubType(typeof(Block), ObjectType.Block)]
+    [JsonSubtypes.KnownSubType(typeof(IBlock), ObjectType.Block)]
     [JsonSubtypes.KnownSubType(typeof(User), ObjectType.User)]
     public interface IObject
     {
diff --git a/Test/Notion.IntegrationTests/IBlocksClientTests.cs b/Test/Notion.IntegrationTests/IBlocksClientTests.cs
index 64d9b332..0db08a7c 100644
--- a/Test/Notion.IntegrationTests/IBlocksClientTests.cs
+++ b/Test/Notion.IntegrationTests/IBlocksClientTests.cs
@@ -40,7 +40,7 @@ public async Task AppendChildrenAsync_AppendsBlocksGivenBlocks()
                 page.Id,
                 new BlocksAppendChildrenParameters
                 {
-                    Children = new List<Block>()
+                    Children = new List<IBlock>()
                     {
                         new BreadcrumbBlock
                         {
@@ -100,7 +100,7 @@ public async Task UpdateBlockAsync_UpdatesGivenBlock()
                 page.Id,
                 new BlocksAppendChildrenParameters
                 {
-                    Children = new List<Block>()
+                    Children = new List<IBlock>()
                     {
                         new BreadcrumbBlock
                         {
@@ -141,7 +141,7 @@ public async Task DeleteAsync_DeleteBlockWithGivenId()
                 page.Id,
                 new BlocksAppendChildrenParameters
                 {
-                    Children = new List<Block>()
+                    Children = new List<IBlock>()
                     {
                         new DividerBlock
                         {
@@ -166,7 +166,7 @@ public async Task DeleteAsync_DeleteBlockWithGivenId()
 
         [Theory]
         [MemberData(nameof(BlockData))]
-        public async Task UpdateAsync_UpdatesGivenBlock(Block block, IUpdateBlock updateBlock, Action<Block> assert)
+        public async Task UpdateAsync_UpdatesGivenBlock(IBlock block, IUpdateBlock updateBlock, Action<IBlock> assert)
         {
             var pageParentId = "3c357473a28149a488c010d2b245a589";
 
@@ -183,7 +183,7 @@ public async Task UpdateAsync_UpdatesGivenBlock(Block block, IUpdateBlock update
                 page.Id,
                 new BlocksAppendChildrenParameters
                 {
-                    Children = new List<Block>()
+                    Children = new List<IBlock>()
                     {
                         block
                     }
@@ -245,7 +245,7 @@ private static IEnumerable<object[]> BlockData()
                             }
                         }
                     },
-                    new Action<Block>((block) => {
+                    new Action<IBlock>((block) => {
                         var updatedBlock = (BookmarkBlock)block;
                         Assert.Equal("https://github.com/notion-dotnet/notion-sdk-net", updatedBlock.Bookmark.Url);
                         Assert.Equal("Github", updatedBlock.Bookmark.Caption.OfType<RichTextText>().First().Text.Content);
@@ -265,7 +265,7 @@ private static IEnumerable<object[]> BlockData()
                             Expression = "e=mc^2"
                         }
                     },
-                    new Action<Block>((block) => {
+                    new Action<IBlock>((block) => {
                         var updatedBlock = (EquationBlock)block;
                         Assert.Equal("e=mc^2", updatedBlock.Equation.Expression);
                     })
@@ -275,7 +275,7 @@ private static IEnumerable<object[]> BlockData()
                         Divider = new DividerBlock.Data()
                     },
                     new DividerUpdateBlock(),
-                    new Action<Block>((block) => {
+                    new Action<IBlock>((block) => {
                         Assert.NotNull(block);
                         Assert.IsType<DividerBlock>(block);
                     })
@@ -295,7 +295,7 @@ private static IEnumerable<object[]> BlockData()
                             }
                         }
                     },
-                    new Action<Block>((block) => {
+                    new Action<IBlock>((block) => {
                         block.Should().NotBeNull();
 
                         block.Should().BeOfType<AudioBlock>().Subject
@@ -309,7 +309,7 @@ private static IEnumerable<object[]> BlockData()
                         TableOfContents = new TableOfContentsBlock.Data()
                     },
                     new TableOfContentsUpdateBlock(),
-                    new Action<Block>((block) =>
+                    new Action<IBlock>((block) =>
                     {
                         Assert.NotNull(block);
                         Assert.IsType<TableOfContentsBlock>(block);
@@ -349,7 +349,7 @@ private static IEnumerable<object[]> BlockData()
                             }
                         }
                     },
-                    new Action<Block>((block) =>
+                    new Action<IBlock>((block) =>
                     {
                         Assert.NotNull(block);
                         var calloutBlock = Assert.IsType<CalloutBlock>(block);
@@ -391,7 +391,7 @@ private static IEnumerable<object[]> BlockData()
                             }
                         }
                     },
-                    new Action<Block>((block) =>
+                    new Action<IBlock>((block) =>
                     {
                         Assert.NotNull(block);
                         var quoteBlock = Assert.IsType<QuoteBlock>(block);
diff --git a/Test/Notion.UnitTests/BlocksClientTests.cs b/Test/Notion.UnitTests/BlocksClientTests.cs
index cb1b0f99..3e1a1b53 100644
--- a/Test/Notion.UnitTests/BlocksClientTests.cs
+++ b/Test/Notion.UnitTests/BlocksClientTests.cs
@@ -59,7 +59,7 @@ public async Task AppendBlockChildren()
 
             var parameters = new BlocksAppendChildrenParameters()
             {
-                Children = new List<Block>
+                Children = new List<IBlock>
                 {
                     new HeadingTwoBlock()
                     {