Habitat partitioning by bottlenose dolphins (Tursiops truncatus), short-beaked common dolphins (Delphinus delphis), and long-beaked common dolphins (D. capensis), were assessed during 178 surveys conducted between 1997–2000 in Santa Monica Bay, California. Bottlenose dolphins were found year-round within 0.5 km from shore in 80.0 % of the sightings (n = 137) but they were also found in deeper waters further offshore. The two common dolphin species were observed year-round (n = 83) far from shore and near escarpments; they were sympatric but never seen in mixed schools. This study suggests that habitat partitioning in the bay probably relates to resource partitioning among three dolphins species with roughly similar ecological needs.