A survey on San Nicolas Island found a cluster of over 4,200 shell beads associated with Middle Holocene archaeological deposits eroded from a coastal dune at CA-SNI-12. Among the 12 bead types recovered were more than 146 Olivella Grooved Rectangle (OGR) beads, including a previously unknown subtype with diagonal grooves, >3,000 Olivella cap beads, and nearly 400 Olivella spire-removed beads. Direct AMS radiocarbon dates (~5,000 cal B.P.) on two bead fragments con rm the Middle Holocene age of the feature. Between approximately 5,400 and 4,400 cal B.P., California’s southern Channel Islands appear to have been the focal point of OGR bead production and use, though these beads have been found in a variety of archaeological contexts across western North America. The broad distribution but short temporal duration of these beads makes them an important Middle Holocene indicator of bead production and exchange in California and the Great Basin.