He was considered a functionalist, and thought about society as tending towards self regulation and self sufficiency, satisfying determined basic necessities, such as preservation of social order, supplying basic goods and services and child protection. According to the theory of functionalism, society is an organism in which each part fulfills a specific purpose and accomplishes a function. All of society’s members cooperate by accomplishing its necessities because they have common values and objectives. His most important contributions are: Structure of Social Action, 1937, Social System, 1951, and Societies: Evolve and compared perspectives (1966). Parsons developed his theory on the organization of the social system in terms of structure and function. Structure includes relatively constant and stable elements such as individual roles (father, teacher, etc.), collective roles (such as family, political parties, factories, etc), and norms (models) and values.