diff --git a/src/AcDream.Core.Net/Messages/InteractRequests.cs b/src/AcDream.Core.Net/Messages/InteractRequests.cs
index d9cfe7b..68b3b1e 100644
--- a/src/AcDream.Core.Net/Messages/InteractRequests.cs
+++ b/src/AcDream.Core.Net/Messages/InteractRequests.cs
@@ -29,6 +29,7 @@ public static class InteractRequests
     public const uint UseOpcode = 0x0036u;
     public const uint UseWithTargetOpcode = 0x0035u;
     public const uint TeleToLifestoneOpcode = 0x0063u;
+    public const uint PutItemInContainerOpcode = 0x0019u;
 
     /// <summary>
     /// Use an object: click a door, loot a corpse, talk to an NPC,
@@ -73,4 +74,36 @@ public static class InteractRequests
         BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  TeleToLifestoneOpcode);
         return body;
     }
+
+    /// <summary>
+    /// Pick up a ground item or move an item between containers. The
+    /// server places the item in <paramref name="containerGuid"/> at
+    /// the given <paramref name="placement"/> slot (pass 0 to let the
+    /// server choose). For F-key ground-pickup, pass the player's own
+    /// server guid as <paramref name="containerGuid"/>.
+    ///
+    /// <para>
+    /// Wire layout (ACE GameActionPutItemInContainer.Handle):
+    /// <code>
+    ///   u32 0xF7B1
+    ///   u32 gameActionSequence
+    ///   u32 0x0019                 // PutItemInContainer
+    ///   u32 itemGuid               // server guid of the item
+    ///   u32 containerGuid          // destination container (player or bag)
+    ///   i32 placement              // 0 = server picks slot
+    /// </code>
+    /// </para>
+    /// </summary>
+    public static byte[] BuildPickUp(
+        uint gameActionSequence, uint itemGuid, uint containerGuid, int placement)
+    {
+        byte[] body = new byte[24];
+        BinaryPrimitives.WriteUInt32LittleEndian(body,            GameActionEnvelope);
+        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(4),  gameActionSequence);
+        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(8),  PutItemInContainerOpcode);
+        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(12), itemGuid);
+        BinaryPrimitives.WriteUInt32LittleEndian(body.AsSpan(16), containerGuid);
+        BinaryPrimitives.WriteInt32LittleEndian (body.AsSpan(20), placement);
+        return body;
+    }
 }
diff --git a/tests/AcDream.Core.Net.Tests/Messages/InteractRequestsTests.cs b/tests/AcDream.Core.Net.Tests/Messages/InteractRequestsTests.cs
index 5e99b5d..f251cf4 100644
--- a/tests/AcDream.Core.Net.Tests/Messages/InteractRequestsTests.cs
+++ b/tests/AcDream.Core.Net.Tests/Messages/InteractRequestsTests.cs
@@ -42,4 +42,28 @@ public sealed class InteractRequestsTests
         Assert.Equal(InteractRequests.TeleToLifestoneOpcode,
             BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(8)));
     }
+
+    [Fact]
+    public void BuildPickUp_WritesOpcode0x0019AndPayload()
+    {
+        byte[] body = InteractRequests.BuildPickUp(
+            gameActionSequence: 5,
+            itemGuid:           0xABCDu,
+            containerGuid:      0x5000000Au,
+            placement:          0);
+
+        Assert.Equal(24, body.Length);
+        Assert.Equal(InteractRequests.GameActionEnvelope,
+            BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(0)));
+        Assert.Equal(5u,
+            BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(4)));
+        Assert.Equal(InteractRequests.PutItemInContainerOpcode,
+            BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(8)));
+        Assert.Equal(0xABCDu,
+            BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(12)));
+        Assert.Equal(0x5000000Au,
+            BinaryPrimitives.ReadUInt32LittleEndian(body.AsSpan(16)));
+        Assert.Equal(0,
+            BinaryPrimitives.ReadInt32LittleEndian(body.AsSpan(20)));
+    }
 }