This chapter outlines six sociological theories of social change. The first and oldest is evolutionary theory, loosely based on the Darwinian ideas of biological and organism growth from simple to complex. Second, functionalist theory, with its emphasis on what maintains society, is described. The third theory is conflict theory, which stands in contrast to evolutionary ideas and describes how societies resist change. The fourth theory is the economic theory of Karl Marx who suggests that social change occurs because of the contradiction between the constantly changing and developing production forces and the stable production/class relationships. The fifth theory is cyclical theory, which suggests that societies rise and fall in a predictable fashion. Finally, deterministic theories that focus on the causes of social change are described.