Since social systems are attributes of society and personality systems are attributes of individuals, it was formerly assumed, both by anthropologists and by psychologists, that there was little relationship between “the acts of individuals” and the “regularities of social process.” Classical cultural determinism, for example, attributed efficient causation to the cultural heritage—people perform this or that activity of the social system “because it’s part of their culture.” This chapter shows that there is an intimate relationship between social systems and personality: social systems operate by means of personality, and personality functions by means of social systems. If social sanctions are not the primary means of achieving cultural conformity, it is because social roles, though prescribed, satisfy personality needs. Theories of social systems that ignore unconscious motives are not only truncated, but when social analyses which are based on such theories are applied by administrators, they often lead to unfortunate results.