diff -r 23d9daed4b14 Doc/faq/programming.rst
--- a/Doc/faq/programming.rst	Tue Mar 04 23:22:15 2014 +0000
+++ b/Doc/faq/programming.rst	Mon Mar 10 16:39:20 2014 +0000
@@ -391,6 +391,61 @@
 
 the values ``42``, ``314``, and ``somevar`` are arguments.
 
+Are variables assigned by reference or by value?
+------------------------------------------------
+Variables are assigned the value of a reference to an object. However,
+depending on whether an object is mutable or immutable, the behavior of
+assigning a variable to another variable can appear to differ. 
+
+Integers, strings, and tuples are examples of immutable objects. When an 
+immutable object is altered, a new object is created and only the variable where
+the object was created is updated to reference the new object.
+For example::
+
+    >>> x = 1
+    >>> y = x
+    >>> x = x + 1
+    >>> x
+    2
+    >>> y
+    1
+
+Because integers are immutable, ``x`` points to the new object whereas ``y``
+still points to the old object. Here is an example with tuples, which like
+integers are immutable::
+
+    >>> a = (1,2)
+    >>> b = a
+    >>> a = a + (3,)
+    >>> a
+    (1, 2, 3)
+    >>> b
+    (1, 2)
+
+However, if the object being referenced is mutable, then the object can be
+changed with no new object being created, as in the case of list mutation::
+
+    >>> a = [1, 2]
+    >>> b = a
+    >>> a.append(3)
+    >>> a
+    [1, 2, 3]
+    >>> b
+    [1, 2, 3]
+
+In the above example, both variables  ``a`` and ``b`` reference the same object.
+However, it is important to note that although lists are mutable, not all
+operations mutate lists; in the case of concatenating lists, a new list is
+created and therefore the variables ``x`` and ``y`` in the example below
+reference different objects::
+
+    >>> x = [1, 2]
+    >>> y = x
+    >>> x = x + [3]
+    >>> x
+    [1, 2, 3]
+    >>> y
+    [1, 2]
 
 How do I write a function with output parameters (call by reference)?
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