diff --git a/Source/Collections/Deque.Test.cs b/Source/Collections/Deque.Test.cs
index 04f1f5d..e0c737e 100644
--- a/Source/Collections/Deque.Test.cs
+++ b/Source/Collections/Deque.Test.cs
@@ -28,7 +28,8 @@ using NMock2;
 
 namespace Nuclex.Support.Collections {
 
-#if false
+#if true
+
   /// <summary>Unit Test for the double ended queue</summary>
   [TestFixture]
   public class DequeTest {
@@ -93,7 +94,263 @@ namespace Nuclex.Support.Collections {
       }
     }
 
+    /// <summary>
+    ///   Validates that an exception is thrown if the 'First' property is accessed
+    ///   in an empty deque
+    /// </summary>
+    [Test]
+    public void TestThrowOnAccessFirstInEmptyDeque() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.Throws<InvalidOperationException>(
+        delegate() { Console.WriteLine(intDeque.First); }
+      );
+    }
+
+    /// <summary>
+    ///   Validates that an exception is thrown if the 'Last' property is accessed
+    ///   in an empty deque
+    /// </summary>
+    [Test]
+    public void TestThrowOnAccessLastInEmptyDeque() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.Throws<InvalidOperationException>(
+        delegate() { Console.WriteLine(intDeque.Last); }
+      );
+    }
+
+    /// <summary>
+    ///   Validates that an exception is thrown if the first item is attempted to be 
+    ///   removed from an empty deque
+    /// </summary>
+    [Test]
+    public void TestThrowOnRemoveFirstFromEmptyDeque() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.Throws<InvalidOperationException>(
+        delegate() { intDeque.RemoveFirst(); }
+      );
+    }
+
+    /// <summary>
+    ///   Validates that an exception is thrown if the last item is attempted to be 
+    ///   removed from an empty deque
+    /// </summary>
+    [Test]
+    public void TestThrowOnRemoveLastFromEmptyDeque() {
+      Deque<int> intDeque = new Deque<int>();
+      Assert.Throws<InvalidOperationException>(
+        delegate() { intDeque.RemoveLast(); }
+      );
+    }
+    
+    /// <summary>
+    ///   Tests whether the Insert() method of the deque can insert an item at
+    ///   the end of the deque
+    /// </summary>
+    [Test]
+    public void TestInsertAtEnd() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 48; ++item) {
+        intDeque.AddLast(item);
+      }
+      
+      intDeque.Insert(intDeque.Count, 12345);
+
+      Assert.AreEqual(12345, intDeque.Last);
+    }
+
+    /// <summary>
+    ///   Tests whether the Insert() method of the deque can insert an item into
+    ///   the last block of the deque when that last block is already full
+    /// </summary>
+    [Test]
+    public void TestInsertInLastBlock() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 48; ++item) {
+        intDeque.AddLast(item);
+      }
+
+      intDeque.Insert(45, 12345);
+
+      Assert.AreEqual(49, intDeque.Count);
+      for(int index = 0; index < 44; ++index) {
+        Assert.AreEqual(index, intDeque[index]);
+      }
+      Assert.AreEqual(12345, intDeque[45]);
+      for(int index = 46; index < 49; ++index) {
+        Assert.AreEqual(index - 1, intDeque[index]);
+      }
+    }
+
+    /// <summary>
+    ///   Tests whether the Insert() method of the deque can insert an item into
+    ///   the second-to-last block of the deque
+    /// </summary>
+    [Test]
+    public void TestInsertInSecondToLastBlock() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 40; ++item) {
+        intDeque.AddLast(item);
+      }
+      
+      intDeque.Insert(24, 12345);
+
+      Assert.AreEqual(41, intDeque.Count);
+      for(int index = 0; index < 24; ++index) {
+        Assert.AreEqual(index, intDeque[index]);
+      }
+      Assert.AreEqual(12345, intDeque[24]);
+      for(int index = 25; index < 41; ++index) {
+        Assert.AreEqual(index - 1, intDeque[index]);
+      }
+    }
+
+    /// <summary>
+    ///   Tests whether the Insert() method of the deque can insert an item into
+    ///   the third-to-last block of the deque
+    /// </summary>
+    [Test]
+    public void TestInsertInThirdToLastBlock() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 40; ++item) {
+        intDeque.AddLast(item);
+      }
+
+      intDeque.Insert(8, 12345);
+
+      Assert.AreEqual(41, intDeque.Count);
+
+      for(int index = 0; index < 8; ++index) {
+        Assert.AreEqual(index, intDeque[index]);
+      }
+      Assert.AreEqual(12345, intDeque[8]);
+      for(int index = 9; index < 41; ++index) {
+        Assert.AreEqual(index - 1, intDeque[index]);
+      }
+    }
+
+    /// <summary>
+    ///   Tests whether the RemoveAt() method of the deque can remove an item from
+    ///   the end of the deque
+    /// </summary>
+    [Test]
+    public void TestRemoveAtEnd() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 48; ++item) {
+        intDeque.AddLast(item);
+      }
+
+      intDeque.RemoveAt(intDeque.Count - 1);
+
+      Assert.AreEqual(46, intDeque.Last);
+    }
+
+    /// <summary>
+    ///   Tests whether the RemoveAt() method of the deque can remove an item
+    ///   from the last block of the deque
+    /// </summary>
+    [Test]
+    public void TestRemoveFromLastBlock() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 48; ++item) {
+        intDeque.AddLast(item);
+      }
+
+      intDeque.RemoveAt(45);
+
+      Assert.AreEqual(47, intDeque.Count);
+
+      for(int index = 0; index < 45; ++index) {
+        Assert.AreEqual(index, intDeque[index]);
+      }
+      for(int index = 45; index < 47; ++index) {
+        Assert.AreEqual(index + 1, intDeque[index]);
+      }
+    }
+
+    /// <summary>
+    ///   Tests whether the RemoveAt() method of the deque can remove an item from
+    ///   the second-to-last block of the deque
+    /// </summary>
+    [Test]
+    public void TestRemoveFromSecondToLastBlock() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 40; ++item) {
+        intDeque.AddLast(item);
+      }
+
+      intDeque.RemoveAt(24);
+
+      Assert.AreEqual(39, intDeque.Count);
+
+      for(int index = 0; index < 24; ++index) {
+        Assert.AreEqual(index, intDeque[index]);
+      }
+      for(int index = 24; index < 39; ++index) {
+        Assert.AreEqual(index + 1, intDeque[index]);
+      }
+    }
+
+    /// <summary>
+    ///   Tests whether the RemoveAt() method of the deque can remove an item from
+    ///   the third-to-last block of the deque
+    /// </summary>
+    [Test]
+    public void TestRemoveFromThirdToLastBlock() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 33; ++item) {
+        intDeque.AddLast(item);
+      }
+
+      intDeque.RemoveAt(8);
+
+      Assert.AreEqual(32, intDeque.Count);
+
+      for(int index = 0; index < 8; ++index) {
+        Assert.AreEqual(index, intDeque[index]);
+      }
+      for(int index = 8; index < 32; ++index) {
+        Assert.AreEqual(index + 1, intDeque[index]);
+      }
+    }
+    
+    /// <summary>
+    ///   Verifies that items can be assigned by their index
+    /// </summary>
+    [Test]
+    public void TestIndexAssignment() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 32; ++item) {
+        intDeque.AddLast(item);
+      }
+      intDeque[16] = 12345;
+      intDeque[17] = 54321;
+      
+      for(int index = 0; index < 16; ++index) {
+        intDeque.RemoveFirst();
+      }
+
+      Assert.AreEqual(12345, intDeque.First);
+      intDeque.RemoveFirst();
+      Assert.AreEqual(54321, intDeque.First);
+    }
+
+    /// <summary>
+    ///   Verifies that an exception is thrown if an invalid index is accessed
+    /// </summary>
+    [Test]
+    public void TestThrowOnInvalidIndex() {
+      Deque<int> intDeque = new Deque<int>(16);
+      for(int item = 0; item < 32; ++item) {
+        intDeque.AddLast(item);
+      }
+      
+      Assert.Throws<ArgumentOutOfRangeException>(
+        delegate() { Console.WriteLine(intDeque[32]); }
+      );
+    }
+
   }
+
 #endif
 
 } // namespace Nuclex.Support.Collections
diff --git a/Source/Collections/Deque.cs b/Source/Collections/Deque.cs
index 32ead50..18430d5 100644
--- a/Source/Collections/Deque.cs
+++ b/Source/Collections/Deque.cs
@@ -4,7 +4,8 @@ using System.Collections;
 
 namespace Nuclex.Support.Collections {
 
-#if false
+#if true
+
   /// <summary>A double-ended queue that allocates memory in blocks</summary>
   /// <typeparam name="ItemType">Type of the items being stored in the queue</typeparam>
   /// <remarks>
@@ -81,6 +82,8 @@ namespace Nuclex.Support.Collections {
       if(this.count == 0) {
         throw new InvalidOperationException("Cannot remove items from empty deque");
       }
+      
+      // TODO: Zero removed array entry if array is kept
 
       ++this.firstBlockStartIndex;
       if(this.firstBlockStartIndex >= this.blockSize) { // Block became empty
@@ -101,6 +104,8 @@ namespace Nuclex.Support.Collections {
         throw new InvalidOperationException("Cannot remove items from empty deque");
       }
 
+      // TODO: Zero removed array entry if array is kept
+
       --this.lastBlockEndIndex;
       if(this.lastBlockEndIndex == 0) { // Block became empty
         if(this.count > 1) {
@@ -142,17 +147,118 @@ namespace Nuclex.Support.Collections {
       ++this.count;
     }
 
+    /// <summary>Inserts the item at the specified index</summary>
+    /// <param name="index">Index the item will be inserted at</param>
+    /// <param name="item">Item that will be inserted</param>
     public void Insert(int index, ItemType item) {
+      // TODO: Not perfect. Can shift to left or to right in a deque.
+      //       Rewrite!
       if(index == this.count) {
         AddLast(item);
       } else {
         int blockIndex, subIndex;
         findIndex(index, out blockIndex, out subIndex);
 
-        //for(int block = this.blocks.Count - 1; block > 
+        int lastBlock = this.blocks.Count - 1;
+        int blockLength;
+
+        // If the lastmost block is full, we need to add another block
+        if(this.lastBlockEndIndex == this.blockSize) {
+          this.blocks.Add(new ItemType[this.blockSize]);
+          this.blocks[lastBlock + 1][0] = this.blocks[lastBlock][this.blockSize - 1];
+          this.lastBlockEndIndex = 1;
+
+          blockLength = this.blockSize - 1;
+        } else {
+          blockLength = this.lastBlockEndIndex;
+          ++this.lastBlockEndIndex;
+        }
+
+        // If the insertion point is not in the lastmost block
+        if(blockIndex != lastBlock) {
+          Array.Copy(
+            this.blocks[lastBlock], 0, this.blocks[lastBlock], 1, blockLength
+          );
+          this.blocks[lastBlock][0] = this.blocks[lastBlock - 1][this.blockSize - 1];
+
+          // Move all the blocks following the insertion point to the right by one item.
+          // If there are no blocks inbetween, this for loop will not run.
+          for(int tempIndex = lastBlock - 1; tempIndex > blockIndex; --tempIndex) {
+            Array.Copy(
+              this.blocks[tempIndex], 0, this.blocks[tempIndex], 1, this.blockSize - 1
+            );
+            this.blocks[tempIndex][0] = this.blocks[tempIndex - 1][this.blockSize - 1];
+          }
+
+          blockLength = this.blockSize - 1;
+        }
+
+        // Finally, move the items in the block the insertion takes place in
+        Array.Copy(
+          this.blocks[blockIndex], subIndex,
+          this.blocks[blockIndex], subIndex + 1,
+          blockLength - subIndex
+        );
+
+        this.blocks[blockIndex][subIndex] = item;
+        ++this.count;
       }
     }
-    // http://www.codeproject.com/KB/dotnet/ccnetsandcastle.aspx
+
+    /// <summary>Removes the item at the specified index</summary>
+    /// <param name="index">Index of the item that will be removed</param>
+    public void RemoveAt(int index) {
+      // TODO: Not perfect. Can shift to left or to right in a deque.
+      //       Rewrite!
+      if(index == this.count - 1) {
+        RemoveLast();
+      } else {
+        int blockIndex, subIndex;
+        findIndex(index, out blockIndex, out subIndex);
+
+        int lastBlock = this.blocks.Count - 1;
+        int startIndex;
+
+        if(blockIndex < lastBlock) {
+          Array.Copy(
+            this.blocks[blockIndex], subIndex + 1,
+            this.blocks[blockIndex], subIndex,
+            this.blockSize - subIndex - 1
+          );
+          this.blocks[blockIndex][this.blockSize - 1] = this.blocks[blockIndex + 1][0];
+
+          for(int tempIndex = blockIndex + 1; tempIndex < lastBlock; ++tempIndex) {
+            Array.Copy(
+              this.blocks[tempIndex], 1,
+              this.blocks[tempIndex], 0,
+              this.blockSize - 1
+            );
+            this.blocks[tempIndex][this.blockSize - 1] = this.blocks[tempIndex + 1][0];
+          }
+          
+          startIndex = 0;
+        } else {
+          startIndex = subIndex;
+        }
+
+        Array.Copy(
+          this.blocks[lastBlock], startIndex + 1,
+          this.blocks[lastBlock], startIndex,
+          this.lastBlockEndIndex - startIndex - 1
+        );
+
+        if(this.lastBlockEndIndex == 1) {
+          this.blocks.RemoveAt(lastBlock);
+          this.lastBlockEndIndex = this.blockSize;
+        } else {
+          this.blocks[lastBlock][this.lastBlockEndIndex - 1] = default(ItemType);
+          --this.lastBlockEndIndex;
+        }
+
+        --this.count;
+      }
+    }
+
     /*
         public int IndexOf(ItemType item) {
           switch(this.blocks.Count) {
@@ -239,6 +345,7 @@ namespace Nuclex.Support.Collections {
     private int lastBlockEndIndex;
 
   }
+
 #endif
 
 } // namespace Nuclex.Support.Collections
diff --git a/Source/Tracking/TransactionGroup.Test.cs b/Source/Tracking/TransactionGroup.Test.cs
index 6488237..2ee58eb 100644
--- a/Source/Tracking/TransactionGroup.Test.cs
+++ b/Source/Tracking/TransactionGroup.Test.cs
@@ -193,7 +193,7 @@ namespace Nuclex.Support.Tracking {
       this.mockery = new Mockery();
     }
 
-    /// <summary>Validates that the set transaction properly sums the progress</summary>
+    /// <summary>Validates that the transaction group correctly sums the progress</summary>
     [Test]
     public void TestSummedProgress() {
       using(