diff --git a/README.md b/README.md
index 2d3d96b..e76b099 100644
--- a/README.md
+++ b/README.md
@@ -208,6 +208,7 @@ Challenges, solutions, and unit tests are presented in the form of **IPython/Jup
 | Determine the height of a tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_height/height_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_height/height_solution.ipynb) |
 | Create a binary search tree with minimal height from a sorted array | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst_min/bst_min_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst_min/bst_min_solution.ipynb) |
 | Create a linked list for each level of a binary tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_level_lists/tree_level_lists_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_level_lists/tree_level_lists_solution.ipynb) |
+| Check if a binary tree is balanced | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/check_balance/check_balance_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/check_balance/check_balance_solution.ipynb) |
 | Implement a binary search tree | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst/bst_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/bst/bst_solution.ipynb) |
 | Implement depth-first search on a graph |  [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_dfs/dfs_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_dfs/dfs_solution.ipynb) |
 | Implement breadth-first search on a graph | [Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_bfs/bfs_challenge.ipynb)│[Solution](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/graph_bfs/bfs_solution.ipynb) |
@@ -217,7 +218,6 @@ Challenges, solutions, and unit tests are presented in the form of **IPython/Jup
 | Determine the lowest common ancestor of two nodes | [Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md)│[Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md) |
 | Transform a binary tree into a heap | [Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md)│[Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md) |
 | Implement a right and left rotation on a tree | [Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md)│[Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md) |
-| Check if a binary tree is balanced | [Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md)│[Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md) |
 | Check if a binary tree is binary search tree | [Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md)│[Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md) |
 | Add a challenge | [Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md)│[Contribute](https://github.com/donnemartin/interactive-coding-challenges/blob/master/CONTRIBUTING.md) |
 
diff --git a/graphs_trees/check_balance/__init__.py b/graphs_trees/check_balance/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/graphs_trees/check_balance/check_balance_challenge.ipynb b/graphs_trees/check_balance/check_balance_challenge.ipynb
new file mode 100644
index 0000000..3f13284
--- /dev/null
+++ b/graphs_trees/check_balance/check_balance_challenge.ipynb
@@ -0,0 +1,180 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges).</i></small>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Challenge Notebook"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Problem: Check if a binary tree is balanced.\n",
+    "\n",
+    "* [Constraints](#Constraints)\n",
+    "* [Test Cases](#Test-Cases)\n",
+    "* [Algorithm](#Algorithm)\n",
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)\n",
+    "* [Solution Notebook](#Solution-Notebook)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Constraints\n",
+    "\n",
+    "* Is a balanced tree one where the heights of two sub trees of any node doesn't differ by more than 1?\n",
+    "    * Yes\n",
+    "* Can we assume we already have a Node class with an insert method?\n",
+    "    * Yes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "* 5, 3, 8, 1, 4 -> Yes\n",
+    "* 5, 3, 8, 9, 10 -> No"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "\n",
+    "Refer to the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/check_balance/check_balance_solution.ipynb).  If you are stuck and need a hint, the solution notebook's algorithm discussion might be a good place to start."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Code"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "%run ../bst/bst.py\n",
+    "%load ../bst/bst.py"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "def check_balance(root):\n",
+    "    # TODO: Implement me\n",
+    "    pass"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "**The following unit test is expected to fail until you solve the challenge.**"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "# %load test_check_balance.py\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "\n",
+    "class TestCheckBalance(object):\n",
+    "\n",
+    "    def test_check_balance(self):\n",
+    "        node = Node(5)\n",
+    "        insert(node, 3)\n",
+    "        insert(node, 8)\n",
+    "        insert(node, 1)\n",
+    "        insert(node, 4)\n",
+    "        assert_equal(check_balance(node), True)\n",
+    "\n",
+    "        node = Node(5)\n",
+    "        insert(node, 3)\n",
+    "        insert(node, 8)\n",
+    "        insert(node, 9)\n",
+    "        insert(node, 10)\n",
+    "        assert_equal(check_balance(node), False)\n",
+    "\n",
+    "        print('Success: test_check_balance')\n",
+    "\n",
+    "\n",
+    "def main():\n",
+    "    test = TestCheckBalance()\n",
+    "    test.test_check_balance()\n",
+    "\n",
+    "\n",
+    "if __name__ == '__main__':\n",
+    "    main()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Solution Notebook\n",
+    "\n",
+    "Review the [Solution Notebook](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/check_balance/check_balance_solution.ipynb) for a discussion on algorithms and code solutions."
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/graphs_trees/check_balance/check_balance_solution.ipynb b/graphs_trees/check_balance/check_balance_solution.ipynb
new file mode 100644
index 0000000..5c91c88
--- /dev/null
+++ b/graphs_trees/check_balance/check_balance_solution.ipynb
@@ -0,0 +1,218 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "<small><i>This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/interactive-coding-challenges).</i></small>"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Solution Notebook"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Problem: Check if a binary tree is balanced.\n",
+    "\n",
+    "* [Constraints](#Constraints)\n",
+    "* [Test Cases](#Test-Cases)\n",
+    "* [Algorithm](#Algorithm)\n",
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Constraints\n",
+    "\n",
+    "* Is a balanced tree one where the heights of two sub trees of any node doesn't differ by more than 1?\n",
+    "    * Yes\n",
+    "* Can we assume we already have a Node class with an insert method?\n",
+    "    * Yes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Test Cases\n",
+    "\n",
+    "* 5, 3, 8, 1, 4 -> Yes\n",
+    "* 5, 3, 8, 9, 10 -> No"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Algorithm\n",
+    "\n",
+    "The algorithm will be similar to where we get the height of a tree as seen in [here](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/graphs_trees/tree_height/height_solution.ipynb).\n",
+    "\n",
+    "However, we could check whether the tree is balanced while also checking for the heights.\n",
+    "\n",
+    "* Base case: If the root is None, return 0\n",
+    "* Check the height of `root.left`, if -1, return -1\n",
+    "* Check the height of `root.right`, if -1, return -1\n",
+    "* If the height differences is greater than 1, return -1\n",
+    "* Otherwise, return 1 + max(left height, right height)\n",
+    "    \n",
+    "Complexity:\n",
+    "* Time: O(n)\n",
+    "* Space: O(log n)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Code"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "%run ../bst/bst.py"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "def check_balance(root):\n",
+    "    if check_height(root) == -1:\n",
+    "        return False\n",
+    "    else:\n",
+    "        return True\n",
+    "\n",
+    "def check_height(root):\n",
+    "    if root is None:\n",
+    "        return 0\n",
+    "    left_height = check_height(root.left)\n",
+    "    if left_height == -1:\n",
+    "        return -1\n",
+    "    right_height = check_height(root.right)\n",
+    "    if right_height == -1:\n",
+    "        return -1\n",
+    "    diff_height = left_height - right_height\n",
+    "    if abs(diff_height) > 1:\n",
+    "        return -1\n",
+    "    else:\n",
+    "        return 1 + max(left_height, right_height)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Overwriting test_check_balance.py\n"
+     ]
+    }
+   ],
+   "source": [
+    "%%writefile test_check_balance.py\n",
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "\n",
+    "class TestCheckBalance(object):\n",
+    "\n",
+    "    def test_check_balance(self):\n",
+    "        node = Node(5)\n",
+    "        insert(node, 3)\n",
+    "        insert(node, 8)\n",
+    "        insert(node, 1)\n",
+    "        insert(node, 4)\n",
+    "        assert_equal(check_balance(node), True)\n",
+    "\n",
+    "        node = Node(5)\n",
+    "        insert(node, 3)\n",
+    "        insert(node, 8)\n",
+    "        insert(node, 9)\n",
+    "        insert(node, 10)\n",
+    "        assert_equal(check_balance(node), False)\n",
+    "\n",
+    "        print('Success: test_check_balance')\n",
+    "\n",
+    "\n",
+    "def main():\n",
+    "    test = TestCheckBalance()\n",
+    "    test.test_check_balance()\n",
+    "\n",
+    "\n",
+    "if __name__ == '__main__':\n",
+    "    main()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Success: test_check_balance\n"
+     ]
+    }
+   ],
+   "source": [
+    "%run -i test_check_balance.py"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/graphs_trees/check_balance/test_check_balance.py b/graphs_trees/check_balance/test_check_balance.py
new file mode 100644
index 0000000..b63de5c
--- /dev/null
+++ b/graphs_trees/check_balance/test_check_balance.py
@@ -0,0 +1,30 @@
+from nose.tools import assert_equal
+
+
+class TestCheckBalance(object):
+
+    def test_check_balance(self):
+        node = Node(5)
+        insert(node, 3)
+        insert(node, 8)
+        insert(node, 1)
+        insert(node, 4)
+        assert_equal(check_balance(node), True)
+
+        node = Node(5)
+        insert(node, 3)
+        insert(node, 8)
+        insert(node, 9)
+        insert(node, 10)
+        assert_equal(check_balance(node), False)
+
+        print('Success: test_check_balance')
+
+
+def main():
+    test = TestCheckBalance()
+    test.test_check_balance()
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file