diff --git a/tests/Perspex.Controls.UnitTests/Perspex.Controls.UnitTests.csproj b/tests/Perspex.Controls.UnitTests/Perspex.Controls.UnitTests.csproj
index a41cec398c..29cd92b135 100644
--- a/tests/Perspex.Controls.UnitTests/Perspex.Controls.UnitTests.csproj
+++ b/tests/Perspex.Controls.UnitTests/Perspex.Controls.UnitTests.csproj
@@ -85,6 +85,7 @@
     <Compile Include="ContentPresenterTests.cs" />
     <Compile Include="BorderTests.cs" />
     <Compile Include="Mixins\SelectableMixinTests.cs" />
+    <Compile Include="StackPanelTests.cs" />
     <Compile Include="Primitives\TrackTests.cs" />
     <Compile Include="Primitives\PopupTests.cs" />
     <Compile Include="DropDownTests.cs" />
diff --git a/tests/Perspex.Controls.UnitTests/StackPanelTests.cs b/tests/Perspex.Controls.UnitTests/StackPanelTests.cs
new file mode 100644
index 0000000000..4b96aa3357
--- /dev/null
+++ b/tests/Perspex.Controls.UnitTests/StackPanelTests.cs
@@ -0,0 +1,150 @@
+// Copyright (c) The Perspex Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Perspex.Controls;
+using Xunit;
+
+namespace Perspex.Controls.UnitTests
+{
+    public class StackPanelTests
+    {
+        [Fact]
+        public void Lays_Out_Children_Vertically()
+        {
+            var target = new StackPanel
+            {
+                Children = new Controls
+                {
+                    new Border { Height = 20, Width = 120 },
+                    new Border { Height = 30 },
+                    new Border { Height = 50 },
+                }
+            };
+
+            target.Measure(Size.Infinity);
+            target.Arrange(new Rect(target.DesiredSize));
+
+            Assert.Equal(new Size(120, 100), target.Bounds.Size);
+            Assert.Equal(new Rect(0, 0, 120, 20), target.Children[0].Bounds);
+            Assert.Equal(new Rect(0, 20, 120, 30), target.Children[1].Bounds);
+            Assert.Equal(new Rect(0, 50, 120, 50), target.Children[2].Bounds);
+        }
+
+        [Fact]
+        public void Lays_Out_Children_Horizontally()
+        {
+            var target = new StackPanel
+            {
+                Orientation = Orientation.Horizontal,
+                Children = new Controls
+                {
+                    new Border { Width = 20, Height = 120 },
+                    new Border { Width = 30 },
+                    new Border { Width = 50 },
+                }
+            };
+
+            target.Measure(Size.Infinity);
+            target.Arrange(new Rect(target.DesiredSize));
+
+            Assert.Equal(new Size(100, 120), target.Bounds.Size);
+            Assert.Equal(new Rect(0, 0, 20, 120), target.Children[0].Bounds);
+            Assert.Equal(new Rect(20, 0, 30, 120), target.Children[1].Bounds);
+            Assert.Equal(new Rect(50, 0, 50, 120), target.Children[2].Bounds);
+        }
+
+        [Fact]
+        public void Lays_Out_Children_Vertically_With_Gap()
+        {
+            var target = new StackPanel
+            {
+                Gap = 10,
+                Children = new Controls
+                {
+                    new Border { Height = 20, Width = 120 },
+                    new Border { Height = 30 },
+                    new Border { Height = 50 },
+                }
+            };
+
+            target.Measure(Size.Infinity);
+            target.Arrange(new Rect(target.DesiredSize));
+
+            Assert.Equal(new Size(120, 130), target.Bounds.Size);
+            Assert.Equal(new Rect(0, 0, 120, 20), target.Children[0].Bounds);
+            Assert.Equal(new Rect(0, 30, 120, 30), target.Children[1].Bounds);
+            Assert.Equal(new Rect(0, 70, 120, 50), target.Children[2].Bounds);
+        }
+
+        [Fact]
+        public void Lays_Out_Children_Horizontally_With_Gap()
+        {
+            var target = new StackPanel
+            {
+                Gap = 10,
+                Orientation = Orientation.Horizontal,
+                Children = new Controls
+                {
+                    new Border { Width = 20, Height = 120 },
+                    new Border { Width = 30 },
+                    new Border { Width = 50 },
+                }
+            };
+
+            target.Measure(Size.Infinity);
+            target.Arrange(new Rect(target.DesiredSize));
+
+            Assert.Equal(new Size(130, 120), target.Bounds.Size);
+            Assert.Equal(new Rect(0, 0, 20, 120), target.Children[0].Bounds);
+            Assert.Equal(new Rect(30, 0, 30, 120), target.Children[1].Bounds);
+            Assert.Equal(new Rect(70, 0, 50, 120), target.Children[2].Bounds);
+        }
+
+        [Fact]
+        public void Lays_Out_Children_Vertically_Even_If_Larger_Than_Panel()
+        {
+            var target = new StackPanel
+            {
+                Height = 60,
+                Children = new Controls
+                {
+                    new Border { Height = 20, Width = 120 },
+                    new Border { Height = 30 },
+                    new Border { Height = 50 },
+                }
+            };
+
+            target.Measure(Size.Infinity);
+            target.Arrange(new Rect(target.DesiredSize));
+
+            Assert.Equal(new Size(120, 60), target.Bounds.Size);
+            Assert.Equal(new Rect(0, 0, 120, 20), target.Children[0].Bounds);
+            Assert.Equal(new Rect(0, 20, 120, 30), target.Children[1].Bounds);
+            Assert.Equal(new Rect(0, 50, 120, 50), target.Children[2].Bounds);
+        }
+
+        [Fact]
+        public void Lays_Out_Children_Horizontally_Even_If_Larger_Than_Panel()
+        {
+            var target = new StackPanel
+            {
+                Width = 60,
+                Orientation = Orientation.Horizontal,
+                Children = new Controls
+                {
+                    new Border { Width = 20, Height = 120 },
+                    new Border { Width = 30 },
+                    new Border { Width = 50 },
+                }
+            };
+
+            target.Measure(Size.Infinity);
+            target.Arrange(new Rect(target.DesiredSize));
+
+            Assert.Equal(new Size(60, 120), target.Bounds.Size);
+            Assert.Equal(new Rect(0, 0, 20, 120), target.Children[0].Bounds);
+            Assert.Equal(new Rect(20, 0, 30, 120), target.Children[1].Bounds);
+            Assert.Equal(new Rect(50, 0, 50, 120), target.Children[2].Bounds);
+        }
+    }
+}