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This report is preliminary and has not been edited or reviewed for conformity with Geological Survey standards and nomenclature As part of the Louisiana Barrier-Island Erosion Study, a section of one of the barrier islands in the Isles Dernieres chain has been selected for a detailed, multi-year study. The main objective of the study is to determine the nature of the local morphodynamic processes that have produced substantial erosion and landward migration of the islands during, at least, the last 100 years. One of the elements of the study is a beach-profiling program using a highly accurate electronic distance meter. Eleven shore-normal lines spaced along 400 m of the island were surveyed seven times during the period of August 1986 to September 1987 to determine the time and extent of beach change during a year. From that survey data, we have made quantitative estimates of erosion and deposition within the study area. Between August 1986 and September 1987, the beach face migrated approximately 20 m landward along eacJi of the eleven lines. As the amount of material deposited on the backshore (5,600 m) was less than the material lost from the beach face (19,200 m), there was a net loss of sediment from the surveyed area. Because the sand on the surface of the barrier island is only l-to-2-m thick at the berm crest and the change in elevation between the berm crest and the first trough is almost 3 m, some erosion of the underlying muddy marsh deposits occurred (-8,000 m). Although the sand may have remained within the nearshore system, the mud likely dispersed offshore, which contributed significantly to the net loss observed