Understanding the natural dynamics of barrier islands in the key to recognizing and estimation both the short-term and the long-term hazards of living on them. This report summarizes how the barrier islands were created, how they have changed, and why they will continue to change in spite of efforts to halt the natural processes. The Outer Banks of North Carolina are used as an example in this report, but the principles outlined are applicable to other barrier islands on the Atlantic and Gulf coasts.