Decades ago the Diablo Canyon site (CA-SLO-2) on the central California mainland revealed one of the oldest and longest sequences (ca. 9400 radiocarbon years ago to contact) of coastal occupation on the shore of the northeastern Pacific. The artifacts from these important deposits were reported in detail by Greenwood (1972), but only a fraction of the site's faunal collections was analyzed in the original site report. Acquisition of 30 additional radiocarbon dates and analysis of the complete vertebrate fauna have produced a coarse-grained record of human foraging on the California mainland from 8300 cal B.C. to cal A.D. 1769. The temporally controlled faunal matrix, constituting one of the largest trans-Holocene records from western North America, speaks in a meaningful way to two significant issues in hunter-gatherer prehistory: early Holocene foraging strategies and economic intensification/resource depression over time. The site’s earliest component suggests a population invested in watercraft and intensely adapted to the interface of land and sea along the northeastern Pacific coastline. While boats were used to access offshore rocks, terrestrial mammals (e.g., black-tailed deer) were also of primary importance. Dominance of deer throughout the Diablo occupations is inconsistent with recent generalizations about big-game hunting as costly signaling in western North American prehistory. Diachronic variation, correlated with superimposed burials that show growth in human populations through the Holocene, includes: (1) modest incremental changes in most taxa, suggesting resource stability and increasing diet breadth; (2) gradual but significant variation in a few taxa, including the flightless duck which was hunted into extinction and eventually replaced by sea otters; (3) punctuated, multidirectional change during the late Holocene related to historic contingencies of the Medieval Climatic Anomaly and protohistoric disruptions.