In the social sciences specifically sociology and sociocultural anthropology, functionalism, also functional analysis, is a sociological philosophy that originally attempted to explain social institutions as collective means to fill individual biological needs. Later it came to focus on the ways social institutions fill social needs, especially social stability. Functionalism is associated with Émile Durkheim and more recently with Talcott Parsons.

Many functionalists argue that social institutions are functionally integrated to form a stable system and that a change in one institution will precipitate a change in other institutions; expressed by Durkheim and others as an organic analogy. Functionalism, originating as an alternative to historical explanations, was one of the first twentieth century anthropological theories, until it was superseded by structural functional analysis or structural-functionalism.

Structural functionalism takes the view that society consists of parts (e.g. police, hospitals, schools), each of which have their own functions and work together to promote social stability. Structural-functionalism was the dominant perspective of cultural anthropologists and rural sociologists between World War II and the Vietnam War. Along with conflict theory and interactionism functionalism is one of the three major sociological traditions.

A social function is, ‘the contribution made by any phenomenon to a larger system of which the phenomenon is a part.’ This technical usage is not the same as the popular idea of a function as an ‘event/occasion’ or a duty, responsibility, or occupation. A distinction, first made by Robert K. Merton, is made between manifest and latent functions and also between functions with positive (functional or positively functional) and negative (dysfunctional) effects. ‘Any statement explaining an institution as being 'functional or 'dysfunctional' for men[sic] could readily be translated with no loss of meaning into one that said it was 'rewarding' or 'punishing'.’

Functional alternative (also functional equivalent or functional substitute) indicates that, ‘just as the same item may have multiple functions, so may the same function be diversely fulfilled by alternative items.’ The concept may serve as an antidote to ‘the gratuitous assumption of the functional indispensability of particular social structures.’

In the 1960s, functionalism was criticized for being unable to account for social change or structuralist contradictions and conflict and thus often called consensus theory, However, Durkheim used a radical form of guild socialism along with functionalist explanations, Marxism acknowledges social contradictions and uses functionalist explanations, and Parsons' evolutionary theory describes the differentiation and reintegration systems and subsystems and thus at least temporary conflict before reintegration . ‘The fact that functional analysis can be seen by some as inherently conservative and by others as inherently radical suggests that it may be inherently neither one nor the other.’

Stronger criticisms include the epistemological argument that functionalism attempts to describe social institutions solely through their effects and thereby does not explain the cause of those effects, or anything, and the ontological argument that society can not have "needs" as a human being does, and even if society does have needs they need not be met. Anthony Giddens argues that functionalist explanations may all be rewritten as historical accounts of individual human actions and consequences.Prior to social movements in the 1960s, functionalism was the dominant view in sociological thinking; after that time conflict theory challenged the current society, which functionalist theory defended. According to some opponents, functionalist theory contends that conflict and challenge to the status quo is harmful to society, and therefore tends to be the prominent view among conservative thinkers.

Jeffrey Alexander (1985) sees functionalism as a broad school rather than a specific method or system, such as Parson's, which is capable of taking equilibrium (stability) as a reference-point rather than assumption and treats structural differentiation as a major form of social change. ‘The name 'functionalism' implies a difference of method or interpretation that does not exist.’(Davis 1967: 401) This removes the determinism criticized above. Cohen argues that rather than needs a society has dispositional facts: features of the social environment which support the existence of particular social institutions but do not cause them. (ibid)

Famous functionalists include:

• Bronislaw Malinowski
• Alfred Reginald Radcliffe-Brown
• Émile Durkheim
• Talcott Parsons
• Niklas Luhmann
• George Murdoch
• Kinglsey Davis and Wilbert Moore's functional theory of social stratification and Davis' Human Society (1949) and ‘The Myth of Functional Analysis as a Special Method in Sociology and Anthropology’, American Sociological Review (1959).
• Jeffrey Alexander’s Neofunctionalism (1985)
• G. A. Cohen
• Herbert J. Gans’s ‘The Positive Functions of Poverty’, American Journal of Sociology (1972), often taken as parody