diff --git a/spine-csharp/spine-csharp.csproj b/spine-csharp/spine-csharp.csproj
index beff1de63..65297ac44 100644
--- a/spine-csharp/spine-csharp.csproj
+++ b/spine-csharp/spine-csharp.csproj
@@ -60,6 +60,7 @@
   <ItemGroup>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="src\Animation.cs" />
+    <Compile Include="src\AnimationStateData.cs" />
     <Compile Include="src\Atlas.cs" />
     <Compile Include="src\Attachments\AttachmentLoader.cs" />
     <Compile Include="src\Attachments\AtlasAttachmentLoader.cs" />
@@ -68,6 +69,7 @@
     <Compile Include="src\Attachments\RegionAttachment.cs" />
     <Compile Include="src\Bone.cs" />
     <Compile Include="src\BoneData.cs" />
+    <Compile Include="src\AnimationState.cs" />
     <Compile Include="src\Json.cs" />
     <Compile Include="src\Skeleton.cs" />
     <Compile Include="src\SkeletonData.cs" />
diff --git a/spine-csharp/src/AnimationState.cs b/spine-csharp/src/AnimationState.cs
new file mode 100644
index 000000000..c3ea60729
--- /dev/null
+++ b/spine-csharp/src/AnimationState.cs
@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+
+namespace Spine {
+	public class AnimationState {
+		public AnimationStateData Data { get; private set; }
+		public Animation Animation { get; private set; }
+		public float Time { get; set; }
+		public bool Loop { get; set; }
+		private Animation previous;
+		float previousTime;
+		bool previousLoop;
+		float mixTime, mixDuration;
+
+		public AnimationState (AnimationStateData data) {
+			if (data == null) throw new ArgumentNullException("data cannot be null.");
+			Data = data;
+		}
+
+		public void Update (float delta) {
+			Time += delta;
+			previousTime += delta;
+			mixTime += delta;
+		}
+
+		public void Apply (Skeleton skeleton) {
+			if (Animation == null) return;
+			if (previous != null) {
+				previous.Apply(skeleton, previousTime, previousLoop);
+				float alpha = mixTime / mixDuration;
+				if (alpha >= 1) {
+					alpha = 1;
+					previous = null;
+				}
+				Animation.Mix(skeleton, Time, Loop, alpha);
+			} else
+				Animation.Apply(skeleton, Time, Loop);
+		}
+
+		public void SetAnimation (String animationName, bool loop) {
+			Animation animation = Data.SkeletonData.FindAnimation(animationName);
+			if (animation == null) throw new ArgumentException("Animation not found: " + animationName);
+			SetAnimation(animation, loop);
+		}
+
+		public void SetAnimation (Animation animation, bool loop) {
+			previous = null;
+			if (animation != null && Animation != null) {
+				mixDuration = Data.GetMix(Animation, animation);
+				if (mixDuration > 0) {
+					mixTime = 0;
+					previous = Animation;
+					previousTime = Time;
+					previousLoop = Loop;
+				}
+			}
+			Animation = animation;
+			Loop = loop;
+			Time = 0;
+		}
+
+		override public String ToString () {
+			return (Animation != null && Animation.Name != null) ? Animation.Name : base.ToString();
+		}
+	}
+}
diff --git a/spine-csharp/src/AnimationStateData.cs b/spine-csharp/src/AnimationStateData.cs
new file mode 100644
index 000000000..9bb171dbe
--- /dev/null
+++ b/spine-csharp/src/AnimationStateData.cs
@@ -0,0 +1,34 @@
+using System;
+using System.Collections.Generic;
+
+namespace Spine {
+	public class AnimationStateData {
+		public SkeletonData SkeletonData { get; private set; }
+		private Dictionary<KeyValuePair<Animation, Animation>, float> animationToMixTime = new Dictionary<KeyValuePair<Animation, Animation>, float>();
+
+		public AnimationStateData (SkeletonData skeletonData) {
+			SkeletonData = skeletonData;
+		}
+
+		public void SetMix (String fromName, String toName, float duration) {
+			Animation from = SkeletonData.FindAnimation(fromName);
+			if (from == null) throw new ArgumentException("Animation not found: " + fromName);
+			Animation to = SkeletonData.FindAnimation(toName);
+			if (to == null) throw new ArgumentException("Animation not found: " + toName);
+			SetMix(from, to, duration);
+		}
+
+		public void SetMix (Animation from, Animation to, float duration) {
+			if (from == null) throw new ArgumentNullException("from cannot be null.");
+			if (to == null) throw new ArgumentNullException("to cannot be null.");
+			animationToMixTime.Add(new KeyValuePair<Animation, Animation>(from, to), duration);
+		}
+
+		public float GetMix (Animation from, Animation to) {
+			KeyValuePair<Animation, Animation> key = new KeyValuePair<Animation, Animation>(from, to);
+			float duration;
+			animationToMixTime.TryGetValue(key, out duration);
+			return duration;
+		}
+	}
+}
diff --git a/spine-csharp/src/SkeletonJson.cs b/spine-csharp/src/SkeletonJson.cs
index 7e7bb4de5..725c1f10a 100644
--- a/spine-csharp/src/SkeletonJson.cs
+++ b/spine-csharp/src/SkeletonJson.cs
@@ -65,6 +65,7 @@ namespace Spine {
 			SkeletonData skeletonData = new SkeletonData();
 
 			var root = Json.Deserialize(reader) as Dictionary<String, Object>;
+			if (root == null) throw new Exception("Invalid JSON.");
 
 			// Bones.
 			foreach (Dictionary<String, Object> boneMap in (List<Object>)root["bones"]) {
diff --git a/spine-csharp/src/Skin.cs b/spine-csharp/src/Skin.cs
index 78df8ef03..5a65855e3 100644
--- a/spine-csharp/src/Skin.cs
+++ b/spine-csharp/src/Skin.cs
@@ -44,9 +44,9 @@ namespace Spine {
 
 		/** @return May be null. */
 		public Attachment GetAttachment (int slotIndex, String name) {
-			KeyValuePair<int, String> key = new KeyValuePair<int, String>(slotIndex, name);
-			if (!attachments.ContainsKey(key)) return null;
-			return attachments[key];
+			Attachment attachment;
+			attachments.TryGetValue(new KeyValuePair<int, String>(slotIndex, name), out attachment);
+			return attachment;
 		}
 
 		public void FindNamesForSlot (int slotIndex, List<String> names) {