The question over the primacy of either structure or agency in human behavior is a central debate in the social sciences. In this context, agency refers to the capacity of individuals to act independently and to make their own free choices.Structure, in contrast, refers to the recurrent patterned arrangements which influence or limit the choices and opportunities available. The structure versus agency debate may also be understood as an issue of socialisation against autonomy, and can be contrasted with the "nature versus nurture" debate.

The debate over the primacy of structure or agency relates to an issue at the heart of both classical and contemporary sociological theory: the question of social ontology: "What is the social world made of?" "What is a cause of the social world, and what is an effect?" "Do social structures determine an individual's behaviour or does human agency?"

For functionalists such as Émile Durkheim, structure and hierarchy are essential in stabilising the very existence of society. Theorists such as Karl Marx, by contrast, emphasise that the social structure can act to the detriment of the majority of individuals in a society. In both these instances "structure" may refer to something both material (or "economic") and cultural (e.g. related to norms, customs, traditions and ideologies).