A study of the barrier islands and wetlands in the deltaic plain of Louisiana is presented. Its purpose was to document rapid changes and to learn more about the processes responsible and the geologic framework within which they operate. It included systematic collection and analysis of precision nearshore hydrographic data, high resolution seismic profiles, surface sediment samples, continuous vibracores, digital shoreline plots, records of storm overwash events, and analysis of tide gage records to quantify the rise in relative sea level. Results from these studies demonstrate that deltaic progradation, river channel switching, and subsequent rapid erosion accompanying the marine transgression are regular and predictable events along the Mississippi River delta plain and will likely continue in the future. Mitigation measures, such as shoreline nourishment and barrier restoration, that mimic the natural processes may slow the land loss.