Agency: general overview 

According to the Oxford English Dictionary, agency is derived from the Latin 'agentia' which means 'action' and its meaning in the contemporary context boils down to “the ability or capacity to act or exert power” (OED). More specifically, sociologists describe agency as “the power of actors to operate independently of the determining constraints of social structure” and “the volitional, purposive nature of human activity as opposed to its constrained, determined aspects” (Jary and Jary, 1995. p. 10). 

Agency in Social Studies

In the realm of social science, everyday interpretation becomes relevant, when describing individuals who engage in specific actions and thereby influence the social environment. However, scholars studying agency define it in more precise yet varied ways. For instance, Anthony Giddens (1979, 1984)  and Margaret Archer (2003) both characterize agency with a focus on an actor's reflexivity, which is “the regular exercise of the mental ability, shared by all normal people, to consider themselves in relation to their (social) contexts and vice versa” (Archer 2007, p. 4). They assert that agency manifests when individuals consciously choose a course of action in situations where alternative actions are possible. These theorists fundamentally agree on the concept of agency as an individual attribute, particularly centered around reflexivity (Burkitt, 2016).

Apart from their shared fundamental understanding of agency, Archer critiques Giddens for presenting a non-relational view of structure, which he redefines as "rules and resources" (Archer, 1995: 106). In contrast, Archer suggests that critical realists should interpret structure as pertaining to tangible forms of social organization—real entities endowed with their own capabilities, inclinations, and potentials, meaning  (Archer, 1995, p. 106):

The social relations upon which they depend are held to have independent causal properties rather than being mere abstractions from our repetitive and routinised behaviour, and, most importantly, because these relations which constitute structures pre-date occupants of positions within them, thus constraining or enabling agency.

This brings Archer to her widely recognized standpoint that theories of 'structuration' blur the distinction between structure and agency by viewing them as mutually shaping each other. In contrast to Giddens's concept of a 'duality of structure,' Archer (2000) advocates for an 'analytical dualism,' emphasizing the preservation of the relative independence of structure and agency. In this framework, each retains its own generative mechanisms and causal powers.

See also the wiki entry on Agency in Children's Literature. 

References

Archer, M.S. (1995). Realist Social Theory: The Morphogenetic Approach. Cambridge: Cambridge University Press. 

Archer, M.S. (2000). Being Human: The Problem of Agency. Cambridge: Cambridge University Press.

Archer, M.S. (2003). Structure, Agency and the Internal Conversation. Cambridge: Cambridge University Press. 

Archer, M. S. (2007). Making Our Way through the World: Human Reflexivity and Social Mobility. Cambridge and New York: Cambridge University Press.

Burkitt, I. (2016). Relational agency. European Journal of Social Theory, 19(3), 322–339. 

Giddens, A. (1979). Central Problems in Social Theory: Action, Structure and Contradiction in Social Analysis. Basingstoke: Macmillan. 

Giddens, A. (1984). The Constitution of Society: Outline of the Theory of Structuration. Cambridge: Polity Press.

Jary, D. & Jary, J. (1995). Collins dictionary of sociology. 2nd ed. Glasgow: Harper Collins Publishers.

Oxford English Dictionary. (2023). Agency, n. Oxford University Press; Oxford English Dictionary.