Sediment Toxicity, contamination and macrobenthic community structure were examined in 1980 at seven stations along a pollution gradient from the Los Angeles County Sanitation District's sewage outfalls on the Palos Verdes shelf, CA, to control conditions in Santa Monica Bay. Sediment toxicity was determined by laboratory bioassays with the phoxocephalid amphipod, Rhepoxynius abronius. Distribution and abundance of the macrobenthos were generally consistent with the Pearson-Rosenberg model and the Bascom-Mearns-Word quantitative classification of macrobenthic assemblages. Species richness, density, and biomass increased greatly in areas of moderate sediment organic enrichment, but decreased to or below control conditions near the outfalls.