They rejected as simplistic, if not as incorrect, previous theories that located crime causes within individuals. Instead, they argued that the social organization of society constrains what people learn to become and what they might be pressured into doing. Changes in the social context made each of these perspectives reasonable to a significant number of criminologists. For the Chicago School, the rapid growth and increasing diversity of urban America gave legitimacy to a theory that linked crime to these social transformations; for strain theory, the emergence of equal opportunity as a sociopolitical agenda provided an ideal context in which "opportunity theory" could win followers. The history of these perspectives shows how criminological theory can direct, or at least justify, criminal justice policy.