In this paper we use osteological data to evaluate theories about the rise of chiefdoms in southern California. To do this, we examine skeletal evidence for changes in diet, disease and violence in Santa Barbara Channel area populations. These collections date from before and after the development of large, sedentary coastal villages and a political system that facilitated inter-village economic interaction. Our data show that the health consequences of the development of these chiefdoms are comparable to those seen with the development of complex agricultural societies. They also provide insights into the causes of social complexity in non-agricultural societies.