Abstract The sediment budget for a stretch of coast along a barrier chain is calculated through use of historical records, covering a time span of nearly 100 years, mapped short-term changes, and estimates of volume changes caused by physical processes. For the section studied along the southeastern United States, accretion has exceeded erosion. The sediment deficit requires an input at an average rate of 796,000 m 3 (1,041,000 cubic yards) annually. This deficit is partially filled by longshore drift from adjoining sections and by biogenous contributions. Currents are insufficient to carry material from the mainland across the lagoons. Longshore drift and biogenous source cannot account for approximately 337,000 m 3 (441,000 cubic yards) of sediment annually. It is postulated that this material is being moved in from a reservoir on the continental shelf. This reservoir is either the unconsolidated relict sediments or outcrops of poorly consolidated Tertiary rocks which are only thinly veneered by Holocene sediments.