Positive liberty is the possession of the power and resources to act in the context of the structural limitations of the broader society which impacts a person's ability to act, as opposed to negative liberty, which is freedom from external restraint on one's actions.

As Heyman notes, it is important to understand Isaiah Berlin's two definitions of liberty in the context of the ideological circumstances of the 1950's, so a conception of positive liberty includes freedom from external constraints, leading to an understanding of positive liberty in the context of human agency. According to Charles Taylor, Positive liberty is the ability to fulfill one's purposes. Negative liberty is the freedom from interference by others.

The concepts of structure and agency are central to the concept of positive liberty because in order to be free, a person should be free from inhibitions of the social structure in carrying out their ambitions. Structurally, classism, sexism, ageism, ableism and racism can inhibit a person's freedom. As positive liberty is primarily concerned with the possession of sociological agency, it is enhanced by the ability of citizens to participate in government and have their voices, interests, and concerns recognized and acted upon.

Isaiah Berlin's essay "Two Concepts of Liberty" (1958) is typically acknowledged as the first to explicitly draw the distinction between positive and negative liberty.