diff --git a/README.md b/README.md
index 2d5ca524..9520d4c3 100644
--- a/README.md
+++ b/README.md
@@ -103,9 +103,9 @@ var complexFiler = new CompoundFilter(
   - [x] Retrieve a page
   - [x] Create a page
   - [x] Update page
-- [ ] Blocks
+- [x] Blocks
   - [x] Retrieve a block
-  - [ ] Update a block
+  - [x] Update a block
   - [x] Retrieve block children
   - [x] Append block children
 - [x] Users
diff --git a/Src/Notion.Client/Api/ApiEndpoints.cs b/Src/Notion.Client/Api/ApiEndpoints.cs
index 942416fe..e2fa13cf 100644
--- a/Src/Notion.Client/Api/ApiEndpoints.cs
+++ b/Src/Notion.Client/Api/ApiEndpoints.cs
@@ -20,6 +20,7 @@ public static class UsersApiUrls
         public static class BlocksApiUrls
         {
             public static string Retrieve(string blockId) => $"/v1/blocks/{blockId}";
+            public static string Update(string blockId) => $"/v1/blocks/{blockId}";
             public static string RetrieveChildren(string blockId) => $"/v1/blocks/{blockId}/children";
             public static string AppendChildren(string blockId) => $"/v1/blocks/{blockId}/children";
         }
diff --git a/Src/Notion.Client/Api/Blocks/BlocksClient.cs b/Src/Notion.Client/Api/Blocks/BlocksClient.cs
index 9d74ad17..79f7da4d 100644
--- a/Src/Notion.Client/Api/Blocks/BlocksClient.cs
+++ b/Src/Notion.Client/Api/Blocks/BlocksClient.cs
@@ -48,7 +48,7 @@ public async Task<Block> AppendChildrenAsync(string blockId, BlocksAppendChildre
             return await _client.PatchAsync<Block>(url, body);
         }
 
-        public async Task<Block> Retrieve(string blockId)
+        public async Task<Block> RetrieveAsync(string blockId)
         {
             if (string.IsNullOrWhiteSpace(blockId))
             {
@@ -59,5 +59,17 @@ public async Task<Block> Retrieve(string blockId)
 
             return await _client.GetAsync<Block>(url);
         }
+
+        public async Task<Block> UpdateAsync(string blockId, IUpdateBlock updateBlock)
+        {
+            if (string.IsNullOrWhiteSpace(blockId))
+            {
+                throw new ArgumentNullException(nameof(blockId));
+            }
+
+            var url = BlocksApiUrls.Update(blockId);
+
+            return await _client.PatchAsync<Block>(url, updateBlock);
+        }
     }
 }
diff --git a/Src/Notion.Client/Api/Blocks/IBlocksClient.cs b/Src/Notion.Client/Api/Blocks/IBlocksClient.cs
index 6ec10951..9d555c0c 100644
--- a/Src/Notion.Client/Api/Blocks/IBlocksClient.cs
+++ b/Src/Notion.Client/Api/Blocks/IBlocksClient.cs
@@ -9,7 +9,15 @@ public interface IBlocksClient
         /// </summary>
         /// <param name="blockId"></param>
         /// <returns>Block</returns>
-        Task<Block> Retrieve(string blockId);
+        Task<Block> RetrieveAsync(string blockId);
+
+        /// <summary>
+        /// Updates the content for the specified block_id based on the block type.
+        /// </summary>
+        /// <param name="blockId"></param>
+        /// <param name="updateBlock"></param>
+        /// <returns>Block</returns>
+        Task<Block> UpdateAsync(string blockId, IUpdateBlock updateBlock);
 
         Task<PaginatedList<Block>> RetrieveChildrenAsync(string blockId, BlocksRetrieveChildrenParameters parameters = null);
         Task<Block> AppendChildrenAsync(string blockId, BlocksAppendChildrenParameters parameters = null);
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/BulletedListItemBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/BulletedListItemBlock.cs
new file mode 100644
index 00000000..da4ad68d
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/BulletedListItemBlock.cs
@@ -0,0 +1,10 @@
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class BulletedListItemUpdateBlock : IUpdateBlock
+    {
+        [JsonProperty("bulleted_list_item")]
+        public TextContentUpdate BulletedListItem { get; set; }
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingOneBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingOneBlock.cs
new file mode 100644
index 00000000..65c166ad
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingOneBlock.cs
@@ -0,0 +1,10 @@
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class HeadingOneUpdateBlock : IUpdateBlock
+    {
+        [JsonProperty("heading_1")]
+        public TextContentUpdate Heading_1 { get; set; }
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingThreeeBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingThreeeBlock.cs
new file mode 100644
index 00000000..a562391e
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingThreeeBlock.cs
@@ -0,0 +1,10 @@
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class HeadingThreeeUpdateBlock : IUpdateBlock
+    {
+        [JsonProperty("heading_3")]
+        public TextContentUpdate Heading_3 { get; set; }
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingTwoBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingTwoBlock.cs
new file mode 100644
index 00000000..8e2a2bbd
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/HeadingTwoBlock.cs
@@ -0,0 +1,10 @@
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class HeadingTwoUpdateBlock : IUpdateBlock
+    {
+        [JsonProperty("heading_2")]
+        public TextContentUpdate Heading_2 { get; set; }
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/IUpdateBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/IUpdateBlock.cs
new file mode 100644
index 00000000..c28bcf62
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/IUpdateBlock.cs
@@ -0,0 +1,6 @@
+namespace Notion.Client
+{
+    public interface IUpdateBlock
+    {
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/NumberedListItemBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/NumberedListItemBlock.cs
new file mode 100644
index 00000000..a63ed38d
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/NumberedListItemBlock.cs
@@ -0,0 +1,10 @@
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class NumberedListItemUpdateBlock : IUpdateBlock
+    {
+        [JsonProperty("numbered_list_item")]
+        public TextContentUpdate NumberedListItem { get; set; }
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ParagraphBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ParagraphBlock.cs
new file mode 100644
index 00000000..42d103e6
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ParagraphBlock.cs
@@ -0,0 +1,7 @@
+namespace Notion.Client
+{
+    public class ParagraphUpdateBlock : IUpdateBlock
+    {
+        public TextContentUpdate Paragraph { get; set; }
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/TextContentUpdate.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/TextContentUpdate.cs
new file mode 100644
index 00000000..b78f8fbf
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/TextContentUpdate.cs
@@ -0,0 +1,9 @@
+using System.Collections.Generic;
+
+namespace Notion.Client
+{
+    public class TextContentUpdate
+    {
+        public IEnumerable<RichTextBaseInput> Text { get; set; }
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ToDoBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ToDoBlock.cs
new file mode 100644
index 00000000..43b24863
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ToDoBlock.cs
@@ -0,0 +1,19 @@
+using System.Collections.Generic;
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    public class ToDoUpdateBlock : IUpdateBlock
+    {
+        [JsonProperty("to_do")]
+        public Info ToDo { get; set; }
+
+        public class Info
+        {
+            public IEnumerable<RichTextBaseInput> Text { get; set; }
+
+            [JsonProperty("checked")]
+            public bool IsChecked { get; set; }
+        }
+    }
+}
diff --git a/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ToggleBlock.cs b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ToggleBlock.cs
new file mode 100644
index 00000000..e7027add
--- /dev/null
+++ b/Src/Notion.Client/Api/Blocks/RequestParams/BlocksUpdateParameters/UpdateBlocks/ToggleBlock.cs
@@ -0,0 +1,7 @@
+namespace Notion.Client
+{
+    public class ToggleUpdateBlock : IUpdateBlock
+    {
+        public TextContentUpdate Toggle { get; set; }
+    }
+}
diff --git a/Test/Notion.UnitTests/BlocksClientTests.cs b/Test/Notion.UnitTests/BlocksClientTests.cs
index d86c7ec3..e7bc01bd 100644
--- a/Test/Notion.UnitTests/BlocksClientTests.cs
+++ b/Test/Notion.UnitTests/BlocksClientTests.cs
@@ -75,7 +75,51 @@ public async Task RetrieveAsync()
                     .WithBody(jsonData)
             );
 
-            var block = await _client.Retrieve(blockId);
+            var block = await _client.RetrieveAsync(blockId);
+
+            block.Id.Should().Be(blockId);
+            block.HasChildren.Should().BeFalse();
+            block.Type.Should().Be(BlockType.ToDo);
+
+            var todoBlock = ((ToDoBlock)block);
+            todoBlock.ToDo.Text.Should().ContainSingle();
+            todoBlock.ToDo.Text.First().Should().BeAssignableTo<RichTextText>();
+            ((RichTextText)todoBlock.ToDo.Text.First()).Text.Content.Should().Be("Lacinato kale");
+        }
+
+        [Fact]
+        public async Task UpdateAsync()
+        {
+            string blockId = "9bc30ad4-9373-46a5-84ab-0a7845ee52e6";
+            var path = ApiEndpoints.BlocksApiUrls.Update(blockId);
+            var jsonData = await File.ReadAllTextAsync("data/blocks/UpdateBlockResponse.json");
+
+            Server.Given(CreatePatchRequestBuilder(path))
+                .RespondWith(
+                Response.Create()
+                    .WithStatusCode(200)
+                    .WithBody(jsonData)
+            );
+
+            var updateBlock = new ToDoUpdateBlock
+            {
+                ToDo = new ToDoUpdateBlock.Info
+                {
+                    Text = new List<RichTextBaseInput>()
+                    {
+                        new RichTextTextInput
+                        {
+                            Text = new Text
+                            {
+                                Content = "Lacinato kale"
+                            },
+                        }
+                    },
+                    IsChecked = true
+                }
+            };
+
+            var block = await _client.UpdateAsync(blockId, updateBlock);
 
             block.Id.Should().Be(blockId);
             block.HasChildren.Should().BeFalse();
diff --git a/Test/Notion.UnitTests/Notion.UnitTests.csproj b/Test/Notion.UnitTests/Notion.UnitTests.csproj
index 81222651..a9b58659 100644
--- a/Test/Notion.UnitTests/Notion.UnitTests.csproj
+++ b/Test/Notion.UnitTests/Notion.UnitTests.csproj
@@ -30,6 +30,9 @@
     <None Update="data\blocks\RetrieveBlockResponse.json">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
+    <None Update="data\blocks\UpdateBlockResponse.json">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
     <None Update="data\databases\CreateDatabaseResponse.json">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
diff --git a/Test/Notion.UnitTests/data/blocks/UpdateBlockResponse.json b/Test/Notion.UnitTests/data/blocks/UpdateBlockResponse.json
new file mode 100644
index 00000000..c9fb6a9a
--- /dev/null
+++ b/Test/Notion.UnitTests/data/blocks/UpdateBlockResponse.json
@@ -0,0 +1,30 @@
+{
+  "object": "block",
+  "id": "9bc30ad4-9373-46a5-84ab-0a7845ee52e6",
+  "created_time": "2021-03-16T16:31:00.000Z",
+  "last_edited_time": "2021-03-16T16:32:00.000Z",
+  "has_children": false,
+  "type": "to_do",
+  "to_do": {
+    "text": [
+      {
+        "type": "text",
+        "text": {
+          "content": "Lacinato kale",
+          "link": null
+        },
+        "annotations": {
+          "bold": false,
+          "italic": false,
+          "strikethrough": false,
+          "underline": false,
+          "code": false,
+          "color": "default"
+        },
+        "plain_text": "Lacinato kale",
+        "href": null
+      }
+    ],
+    "checked": false
+  }
+}
\ No newline at end of file
diff --git a/docs/README.md b/docs/README.md
index 1e94a60f..b25583b8 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -73,9 +73,9 @@ var complexFiler = new CompoundFilter(
   - [x] Retrieve a page
   - [x] Create a page
   - [x] Update page
-- [ ] Blocks
+- [x] Blocks
   - [x] Retrieve a block
-  - [ ] Update a block
+  - [x] Update a block
   - [x] Retrieve block children
   - [x] Append block children
 - [x] Users