diff --git a/Perspex.Animation/Animatable.cs b/Perspex.Animation/Animatable.cs
index ae5cd56604..bff50a2e46 100644
--- a/Perspex.Animation/Animatable.cs
+++ b/Perspex.Animation/Animatable.cs
@@ -7,7 +7,6 @@
 namespace Perspex.Animation
 {
     using System.Linq;
-    using System.Reactive.Linq;
 
     /// <summary>
     /// Base class for control which can have property transitions.
diff --git a/Perspex.Application/Application.cs b/Perspex.Application/Application.cs
index 06980a4e24..1b94ecaa51 100644
--- a/Perspex.Application/Application.cs
+++ b/Perspex.Application/Application.cs
@@ -28,6 +28,8 @@ namespace Perspex
     /// - A global set of <see cref="Styles"/>.
     /// - A <see cref="FocusManager"/>.
     /// - An <see cref="InputManager"/>.
+    /// - Loads and initializes rendering and windowing subsystems with
+    /// <see cref="InitializeSubsystems(int)"/> and <see cref="InitializeSubsystem(string)"/>.
     /// - Registers services needed by the rest of Perspex in the <see cref="RegisterServices"/>
     /// method.
     /// - Tracks the lifetime of the application.
diff --git a/Perspex.Base/Collections/PerspexListExtensions.cs b/Perspex.Base/Collections/PerspexListExtensions.cs
index 8aaa32a720..331370091e 100644
--- a/Perspex.Base/Collections/PerspexListExtensions.cs
+++ b/Perspex.Base/Collections/PerspexListExtensions.cs
@@ -12,8 +12,25 @@ namespace Perspex.Collections
     using System.ComponentModel;
     using System.Reactive.Disposables;
 
+    /// <summary>
+    /// Defines extension methods for working with <see cref="PerspexList{T}"/>s.
+    /// </summary>
     public static class PerspexListExtensions
     {
+        /// <summary>
+        /// Invokes an action for each item in a collection and subsequently each item added or
+        /// removed from the collection.
+        /// </summary>
+        /// <typeparam name="T">The type of the collection items.</typeparam>
+        /// <param name="collection">The collection.</param>
+        /// <param name="added">
+        /// An action called initially for each item in the collection and subsequently for each
+        /// item added to the collection.
+        /// </param>
+        /// <param name="removed">
+        /// An action called for each item removed from the collection.
+        /// </param>
+        /// <returns>A disposable used to terminate the subscription.</returns>
         public static IDisposable ForEachItem<T>(
             this IPerspexReadOnlyList<T> collection,
             Action<T> added,
@@ -64,6 +81,13 @@ namespace Perspex.Collections
             return Disposable.Create(() => collection.CollectionChanged -= handler);
         }
 
+        /// <summary>
+        /// Listens for property changed events from all items in a collection.
+        /// </summary>
+        /// <typeparam name="T">The type of the collection items.</typeparam>
+        /// <param name="collection">The collection.</param>
+        /// <param name="callback">A callback to call for each property changed event.</param>
+        /// <returns>A disposable used to terminate the subscription.</returns>
         public static IDisposable TrackItemPropertyChanged<T>(
             this IPerspexReadOnlyList<T> collection,
             Action<Tuple<object, PropertyChangedEventArgs>> callback)
diff --git a/Perspex.Base/Diagnostics/PerspexObjectExtensions.cs b/Perspex.Base/Diagnostics/PerspexObjectExtensions.cs
index 7e644f7ebf..2f59749794 100644
--- a/Perspex.Base/Diagnostics/PerspexObjectExtensions.cs
+++ b/Perspex.Base/Diagnostics/PerspexObjectExtensions.cs
@@ -6,8 +6,20 @@
 
 namespace Perspex.Diagnostics
 {
+    /// <summary>
+    /// Defines diagnostic extensions on <see cref="PerspexObject"/>s.
+    /// </summary>
     public static class PerspexObjectExtensions
     {
+        /// <summary>
+        /// Gets a diagnostic for a <see cref="PerspexProperty"/> on a <see cref="PerspexObject"/>.
+        /// </summary>
+        /// <param name="o">The object.</param>
+        /// <param name="property">The property.</param>
+        /// <returns>
+        /// A <see cref="PerspexPropertyValue"/> that can be used to diagnose the state of the
+        /// property on the object.
+        /// </returns>
         public static PerspexPropertyValue GetDiagnostic(this PerspexObject o, PerspexProperty property)
         {
             var set = o.GetSetValues();
diff --git a/Perspex.Base/Diagnostics/PerspexPropertyValue.cs b/Perspex.Base/Diagnostics/PerspexPropertyValue.cs
index ced24be77b..ada68a1d34 100644
--- a/Perspex.Base/Diagnostics/PerspexPropertyValue.cs
+++ b/Perspex.Base/Diagnostics/PerspexPropertyValue.cs
@@ -6,8 +6,19 @@
 
 namespace Perspex.Diagnostics
 {
+    /// <summary>
+    /// Holds diagnostic-related information about the value of a <see cref="PerspexProperty"/>
+    /// on a <see cref="PerspexObject"/>.
+    /// </summary>
     public class PerspexPropertyValue
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PerspexPropertyValue"/> class.
+        /// </summary>
+        /// <param name="property">The property.</param>
+        /// <param name="value">The current property value.</param>
+        /// <param name="priority">The priority of the current value.</param>
+        /// <param name="diagnostic">A diagnostic string.</param>
         public PerspexPropertyValue(
             PerspexProperty property,
             object value,
@@ -20,12 +31,24 @@ namespace Perspex.Diagnostics
             this.Diagnostic = diagnostic;
         }
 
+        /// <summary>
+        /// Gets the property.
+        /// </summary>
         public PerspexProperty Property { get; }
 
+        /// <summary>
+        /// Gets the current property value.
+        /// </summary>
         public object Value { get; }
 
+        /// <summary>
+        /// Gets the priority of the current value.
+        /// </summary>
         public BindingPriority Priority { get; }
 
+        /// <summary>
+        /// Gets a diagnostic string.
+        /// </summary>
         public string Diagnostic { get; }
     }
 }
diff --git a/Perspex.Base/PriorityValue.cs b/Perspex.Base/PriorityValue.cs
index 06d27629c6..b7a808cdc5 100644
--- a/Perspex.Base/PriorityValue.cs
+++ b/Perspex.Base/PriorityValue.cs
@@ -10,7 +10,6 @@ namespace Perspex
     using System.Collections.Generic;
     using System.Linq;
     using System.Reactive.Subjects;
-    using System.Reflection;
     using System.Text;
     using Perspex.Utilities;
 
diff --git a/Perspex.Base/Threading/Dispatcher.cs b/Perspex.Base/Threading/Dispatcher.cs
index b3a7c1d7ea..665a7c753e 100644
--- a/Perspex.Base/Threading/Dispatcher.cs
+++ b/Perspex.Base/Threading/Dispatcher.cs
@@ -11,26 +11,51 @@ namespace Perspex.Threading
     using System.Threading.Tasks;
     using Perspex.Win32.Threading;
 
+    /// <summary>
+    /// Provides services for managing work items on a thread.
+    /// </summary>
+    /// <remarks>
+    /// In Perspex, there is usually only a single <see cref="Dispatcher"/> in the application -
+    /// the one for the UI thread, retrieved via the <see cref="UIThread"/> property.
+    /// </remarks>
     public class Dispatcher
     {
         private static Dispatcher instance = new Dispatcher();
 
         private MainLoop mainLoop = new MainLoop();
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Dispatcher"/> class.
+        /// </summary>
         private Dispatcher()
         {
         }
 
+        /// <summary>
+        /// Gets the <see cref="Dispatcher"/> for the UI thread.
+        /// </summary>
         public static Dispatcher UIThread
         {
             get { return instance; }
         }
 
+        /// <summary>
+        /// Runs the dispatcher's main loop.
+        /// </summary>
+        /// <param name="cancellationToken">
+        /// A cancellation token used to exit the main loop.
+        /// </param>
         public void MainLoop(CancellationToken cancellationToken)
         {
             this.mainLoop.Run(cancellationToken);
         }
 
+        /// <summary>
+        /// Invokes a method on the dispatcher thread.
+        /// </summary>
+        /// <param name="action">The method.</param>
+        /// <param name="priority">The priority with which to invoke the method.</param>
+        /// <returns>A task that can be used to track the method's execution.</returns>
         public Task InvokeAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
         {
             return this.mainLoop.InvokeAsync(action, priority);
diff --git a/Perspex.Base/Threading/DispatcherPriority.cs b/Perspex.Base/Threading/DispatcherPriority.cs
index 00fb1df484..b8fbf84c26 100644
--- a/Perspex.Base/Threading/DispatcherPriority.cs
+++ b/Perspex.Base/Threading/DispatcherPriority.cs
@@ -6,19 +6,65 @@
 
 namespace Perspex.Threading
 {
+    /// <summary>
+    /// Defines the priorities with which jobs can be invoked on a <see cref="Dispatcher"/>.
+    /// </summary>
+    // TODO: These are copied from WPF - many won't apply to Perspex.
     public enum DispatcherPriority
     {
-        Invalid = -1,
+        /// <summary>
+        /// The job will not be processed.
+        /// </summary>
         Inactive = 0,
+
+        /// <summary>
+        /// The job will be processed when the system is idle.
+        /// </summary>
         SystemIdle = 1,
+
+        /// <summary>
+        /// The job will be processed when the application sis idle.
+        /// </summary>
         ApplicationIdle = 2,
+
+        /// <summary>
+        /// The job will be processed after background operations have completed.
+        /// </summary>
         ContextIdle = 3,
+
+        /// <summary>
+        /// The job will be processed after other non-idle operations have completed.
+        /// </summary>
         Background = 4,
+
+        /// <summary>
+        /// The job will be processed with the same priority as input.
+        /// </summary>
         Input = 5,
+
+        /// <summary>
+        /// The job will be processed after layout and render but before input.
+        /// </summary>
         Loaded = 6,
+
+        /// <summary>
+        /// The job will be processed with the same priority as render.
+        /// </summary>
         Render = 7,
+
+        /// <summary>
+        /// The job will be processed with the same priority as data binding.
+        /// </summary>
         DataBind = 8,
+
+        /// <summary>
+        /// The job will be processed with normal priority.
+        /// </summary>
         Normal = 9,
+
+        /// <summary>
+        /// The job will be processed before other asynchronous operations.
+        /// </summary>
         Send = 10,
     }
 }
diff --git a/Perspex.Base/Threading/DispatcherTimer.cs b/Perspex.Base/Threading/DispatcherTimer.cs
index ed14b3499a..78a0e4083e 100644
--- a/Perspex.Base/Threading/DispatcherTimer.cs
+++ b/Perspex.Base/Threading/DispatcherTimer.cs
@@ -11,6 +11,9 @@ namespace Perspex.Threading
     using Perspex.Platform;
     using Splat;
 
+    /// <summary>
+    /// A timer that uses a <see cref="Dispatcher"/> to fire at a specified interval.
+    /// </summary>
     public class DispatcherTimer
     {
         private IDisposable timer;
@@ -19,24 +22,43 @@ namespace Perspex.Threading
 
         private TimeSpan interval;
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DispatcherTimer"/> class.
+        /// </summary>
         public DispatcherTimer()
         {
             this.priority = DispatcherPriority.Normal;
             this.Dispatcher = Dispatcher.UIThread;
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DispatcherTimer"/> class.
+        /// </summary>
+        /// <param name="priority">The priority to use.</param>
         public DispatcherTimer(DispatcherPriority priority)
         {
             this.priority = priority;
             this.Dispatcher = Dispatcher.UIThread;
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DispatcherTimer"/> class.
+        /// </summary>
+        /// <param name="priority">The priority to use.</param>
+        /// <param name="dispatcher">The dispatcher to use.</param>
         public DispatcherTimer(DispatcherPriority priority, Dispatcher dispatcher)
         {
             this.priority = priority;
             this.Dispatcher = dispatcher;
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DispatcherTimer"/> class.
+        /// </summary>
+        /// <param name="interval">The interval at which to tick.</param>
+        /// <param name="priority">The priority to use.</param>
+        /// <param name="dispatcher">The dispatcher to use.</param>
+        /// <param name="callback">The event to call when the timer ticks.</param>
         public DispatcherTimer(TimeSpan interval, DispatcherPriority priority, EventHandler callback, Dispatcher dispatcher)
         {
             this.priority = priority;
@@ -45,6 +67,9 @@ namespace Perspex.Threading
             this.Tick += callback;
         }
 
+        /// <summary>
+        /// Finalizes an instance of the <see cref="DispatcherTimer"/> class.
+        /// </summary>
         ~DispatcherTimer()
         {
             if (this.timer != null)
@@ -53,14 +78,23 @@ namespace Perspex.Threading
             }
         }
 
+        /// <summary>
+        /// Raised when the timer ticks.
+        /// </summary>
         public event EventHandler Tick;
 
+        /// <summary>
+        /// Gets the dispatcher that the timer uses.
+        /// </summary>
         public Dispatcher Dispatcher
         {
             get;
             private set;
         }
 
+        /// <summary>
+        /// Gets or sets the interval at which the timer ticks.
+        /// </summary>
         public TimeSpan Interval
         {
             get
@@ -77,6 +111,9 @@ namespace Perspex.Threading
             }
         }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether the timer is running.
+        /// </summary>
         public bool IsEnabled
         {
             get
@@ -100,12 +137,24 @@ namespace Perspex.Threading
             }
         }
 
+        /// <summary>
+        /// Gets or sets user-defined data associated with the timer.
+        /// </summary>
         public object Tag
         {
             get;
             set;
         }
 
+        /// <summary>
+        /// Starts a new timer.
+        /// </summary>
+        /// <param name="action">
+        /// The method to call on timer tick. If the method returns false, the timer will stop.
+        /// </param>
+        /// <param name="interval">The interval at which to tick.</param>
+        /// <param name="priority">The priority to use.</param>
+        /// <returns>An <see cref="IDisposable"/> used to cancel the timer.</returns>
         public static IDisposable Run(Func<bool> action, TimeSpan interval, DispatcherPriority priority = DispatcherPriority.Normal)
         {
             var timer = new DispatcherTimer(priority);
@@ -124,6 +173,9 @@ namespace Perspex.Threading
             return Disposable.Create(() => timer.Stop());
         }
 
+        /// <summary>
+        /// Starts the timer.
+        /// </summary>
         public void Start()
         {
             if (!this.IsEnabled)
@@ -133,6 +185,9 @@ namespace Perspex.Threading
             }
         }
 
+        /// <summary>
+        /// Stops the timer.
+        /// </summary>
         public void Stop()
         {
             if (this.IsEnabled)
@@ -143,11 +198,17 @@ namespace Perspex.Threading
             }
         }
 
+        /// <summary>
+        /// Raises the <see cref="Tick"/> event on the dispatcher thread.
+        /// </summary>
         private void InternalTick()
         {
             this.Dispatcher.InvokeAsync(this.RaiseTick, this.priority);
         }
 
+        /// <summary>
+        /// Raises the <see cref="Tick"/> event.
+        /// </summary>
         private void RaiseTick()
         {
             if (this.Tick != null)
diff --git a/Perspex.Base/Threading/MainLoop.cs b/Perspex.Base/Threading/MainLoop.cs
index f53aeee5d5..e7efefacc1 100644
--- a/Perspex.Base/Threading/MainLoop.cs
+++ b/Perspex.Base/Threading/MainLoop.cs
@@ -14,6 +14,9 @@ namespace Perspex.Win32.Threading
     using Perspex.Threading;
     using Splat;
 
+    /// <summary>
+    /// A main loop in a <see cref="Dispatcher"/>.
+    /// </summary>
     internal class MainLoop
     {
         private static IPlatformThreadingInterface platform;
@@ -21,11 +24,20 @@ namespace Perspex.Win32.Threading
         private PriorityQueue<Job, DispatcherPriority> queue =
             new PriorityQueue<Job, DispatcherPriority>(PriorityQueueType.Maximum);
 
+        /// <summary>
+        /// Initializes static members of the <see cref="MainLoop"/> class.
+        /// </summary>
         static MainLoop()
         {
             platform = Locator.Current.GetService<IPlatformThreadingInterface>();
         }
 
+        /// <summary>
+        /// Runs the main loop.
+        /// </summary>
+        /// <param name="cancellationToken">
+        /// A cancellation token used to exit the main loop.
+        /// </param>
         public void Run(CancellationToken cancellationToken)
         {
             while (!cancellationToken.IsCancellationRequested)
@@ -64,6 +76,12 @@ namespace Perspex.Win32.Threading
             }
         }
 
+        /// <summary>
+        /// Invokes a method on the main loop.
+        /// </summary>
+        /// <param name="action">The method.</param>
+        /// <param name="priority">The priority with which to invoke the method.</param>
+        /// <returns>A task that can be used to track the method's execution.</returns>
         public Task InvokeAsync(Action action, DispatcherPriority priority)
         {
             var job = new Job(action, priority);
@@ -77,8 +95,16 @@ namespace Perspex.Win32.Threading
             return job.TaskCompletionSource.Task;
         }
 
+        /// <summary>
+        /// A job to run.
+        /// </summary>
         private class Job
         {
+            /// <summary>
+            /// Initializes a new instance of the <see cref="Job"/> class.
+            /// </summary>
+            /// <param name="action">The method to call.</param>
+            /// <param name="priority">The job priority.</param>
             public Job(Action action, DispatcherPriority priority)
             {
                 this.Action = action;
@@ -86,11 +112,20 @@ namespace Perspex.Win32.Threading
                 this.TaskCompletionSource = new TaskCompletionSource<object>();
             }
 
-            public Action Action { get; private set; }
+            /// <summary>
+            /// Gets the method to call.
+            /// </summary>
+            public Action Action { get; }
 
-            public DispatcherPriority Priority { get; private set; }
+            /// <summary>
+            /// Gets the job priority.
+            /// </summary>
+            public DispatcherPriority Priority { get; }
 
-            public TaskCompletionSource<object> TaskCompletionSource { get; set; }
+            /// <summary>
+            /// Gets the task completion source.
+            /// </summary>
+            public TaskCompletionSource<object> TaskCompletionSource { get; }
         }
     }
 }
diff --git a/Perspex.Base/Threading/PerspexScheduler.cs b/Perspex.Base/Threading/PerspexScheduler.cs
index c6c8396eec..a1ebbdcf9b 100644
--- a/Perspex.Base/Threading/PerspexScheduler.cs
+++ b/Perspex.Base/Threading/PerspexScheduler.cs
@@ -8,12 +8,25 @@ namespace Perspex.Threading
 {
     using System;
     using System.Reactive.Concurrency;
-    using System.Reactive.Disposables;
 
+    /// <summary>
+    /// A reactive scheduler that uses Perspex's <see cref="Dispatcher.UIThread"/>.
+    /// </summary>
     public class PerspexScheduler : LocalScheduler
     {
+        /// <summary>
+        /// The instance of the <see cref="PerspexScheduler"/>.
+        /// </summary>
         public static readonly PerspexScheduler Instance = new PerspexScheduler();
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PerspexScheduler"/> class.
+        /// </summary>
+        private PerspexScheduler()
+        {
+        }
+
+        /// <inheritdoc/>
         public override IDisposable Schedule<TState>(TState state, TimeSpan dueTime, Func<IScheduler, TState, IDisposable> action)
         {
             return DispatcherTimer.Run(