diff --git a/SlackNet.Tests/MessageThreadTests.cs b/SlackNet.Tests/MessageThreadTests.cs
new file mode 100644
index 0000000..57b76fb
--- /dev/null
+++ b/SlackNet.Tests/MessageThreadTests.cs
@@ -0,0 +1,49 @@
+using EasyAssertions;
+using Newtonsoft.Json;
+using NUnit.Framework;
+using SlackNet.Events;
+
+namespace SlackNet.Tests;
+
+public class MessageThreadTests
+{
+    private JsonSerializerSettings _sut;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _sut = Default.JsonSettings(Default.SlackTypeResolver(Default.AssembliesContainingSlackTypes)).SerializerSettings;
+    }
+
+    [Test]
+    public void MessageEvent_ThreadReply_HasParentUserId()
+    {
+        var result = Deserialize<Event>(@"{ ""type"": ""message"", ""user"": ""U123ABC456"", ""text"": ""one island"", ""thread_ts"": ""1482960137.003543"", ""parent_user_id"": ""U061F7AUR"", ""ts"": ""1483037603.017503"" }");
+
+        var message = result.ShouldBeA<MessageEvent>().And;
+        message.ParentUserId.ShouldBe("U061F7AUR");
+        message.ExtraProperties.ShouldBeEmpty();
+    }
+
+    [Test]
+    public void MessageEvent_ThreadParent_HasSubscribed()
+    {
+        var result = Deserialize<Event>(@"{ ""type"": ""message"", ""user"": ""U123ABC456"", ""text"": ""island"", ""thread_ts"": ""1482960137.003543"", ""reply_count"": 3, ""subscribed"": true, ""ts"": ""1482960137.003543"" }");
+
+        var message = result.ShouldBeA<MessageEvent>().And;
+        message.Subscribed.ShouldBe(true);
+        message.ExtraProperties.ShouldBeEmpty();
+    }
+
+    [Test]
+    public void MessageEvent_OutsideAThread_HasNoParentUserIdAndIsNotSubscribed()
+    {
+        var result = Deserialize<Event>(@"{ ""type"": ""message"", ""user"": ""U123ABC456"", ""text"": ""Hello"", ""ts"": ""1355517523.000005"" }");
+
+        var message = result.ShouldBeA<MessageEvent>().And;
+        message.ParentUserId.ShouldBeNull();
+        message.Subscribed.ShouldBe(false);
+    }
+
+    private T Deserialize<T>(string json) => JsonConvert.DeserializeObject<T>(json, _sut);
+}
diff --git a/SlackNet/Events/Messages/MessageEvent.cs b/SlackNet/Events/Messages/MessageEvent.cs
index 2b91c26..9f43e83 100644
--- a/SlackNet/Events/Messages/MessageEvent.cs
+++ b/SlackNet/Events/Messages/MessageEvent.cs
@@ -17,6 +17,8 @@ public class MessageEvent : MessageEventBase
     public IList<string> ReplyUsers { get; set; } = [];
     public int ReplyUsersCount { get; set; }
     public string LatestReply { get; set; }
+    public string ParentUserId { get; set; }
+    public bool Subscribed { get; set; }
     public bool IsStarred { get; set; }
     public IList<Reaction> Reactions { get; set; } = [];
     public IList<string> PinnedTo { get; set; } = [];