Prehistoric marine mammal hunting is of interest to archaeologists worldwide because these animals were exploited by a wide range of coastal societies. Sorting out the roles of particular groups of fauna in prehistoric economies requires detailed attention to the analysis of the entire faunal assemblage. Although marine mammals typically provided large quantities of fat and protein and were desirable prey, they were not always central to the diets of the groups that exploited them, particularly in temperate zones. To evaluate effectively the importance of marine mammal exploitation, scholars should calculate the relative contribution of these animals to the economy, identify changes in hunting techniques, determine the relationship between fauna and other aspects of society, assess changing environmental conditions, and consider alternate explanations for those relationships. A large body of research on the northern Channel Islands of California demonstrates that fishing was relatively more important than marine mammal exploitation in subsistence and in stimulating sociopolitical and technological developments. Recent attempts to credit marine mammal hunting as a driving force in the invention of the plank canoe and the evolution of a chiefdom in the Santa Barbara Channel area misunderstand environmental factors and site histories in this region. Rather than assuming that a pan-Pacific Coast set of traditions existed to exploit these taxa, we see evidence of local and regional differences rooted in variable cultural settings, physiographic and oceanographic conditions, and available technologies. Data from the Santa Barbara Channel are used to explore the relationships among marine mammal use, sociological change, and environmental change.