Two radiocarbon dates from CA-SBA-699, a site located near Purisima Point on Vandenberg Air Force Base, indicate that it was occupied for a short interval of time around A.D. 1150. Analysis of a column sample taken from a seacliff exposure of midden deposits revealed that the population occupying this site depended mainly on black turban (Tegula funebralis) and California mussel (Mytilus californianus) for food resources, the former being dietarily more important than the latter. The dominance of black turban appears to reflect unique characteristics of the nearby shellfish communities rather than especially intensive shellfish collecting. Red abalone shells in the midden are reminiscent of Middle Holocene sites on the Channel Islands, where they appear to be indicative of cooler-than-present water temperatures. Their presence at CA-SBA-699, however, may be due to distinctive environmental conditions at Purisima Point. Although the site was occupied at the beginning of an environmentally stressful time known as the Middle-to-Late Period transition, no obvious evidence of subsistence stress is reflected in the faunal remains from the site.