Cetacean occurrence, distribution and behavior were investigated in Santa Monica Bay and nearby areas, California (1997–2007). A total of 425 boat-based surveys documented three species inhabiting the study area year-round - the common bottlenose dolphin, Tursiops truncatus, the long-beaked common dolphin, Delphinus capensis, and the short-beaked common dolphin, D. delphis, and ten species occurring occasionally. Coastal bottlenose dolphins were mostly found traveling, diving and feeding in waters within 0.5km of shore in 81.4% of the sightings (n  =  221), but were also observed occasionally in offshore waters. All other species were seen > 0.5 km of shore, often feeding near escarpments and submarine canyons. Endangered species, such as blue whales (Balaenoptera musculus) and humpback whales (Megaptera novaeangliae), were also recorded in the study area. This paper provides new information as well as an update on data of the composition for the local cetacean community, and offers information that should be considered in the decision-making process associated with the newly established MPAs, and their use. The presence of a diverse cetacean fauna moving in and out the boundaries of these MPAs, also suggests the need for long-term and regular cetacean monitoring in the area.