making an object that "is" an arrayList have an IList interface

I have an object that just holds an arrayList of other objects and some methods to operate on it. What I want to do is basically fill a listBox with the the values of a member string of the objects contained in the arrayList object. so I say listBox.DataSource = "arrayListObject"; listBox.DisplayMember = "memberString"; I get a runtime exception though that states that my arrayListObject doesn't have an IList interface, so it can't serve as a DataSource for the listBox.