Symbolic interactionism is a social psychological theory developed from the work of Charles Horton Cooley and George Herbert Mead in the early part of the twentieth century (the actual name of the theory comes from Herbert Blumer, one of Mead's students). According to this theory, people inhabit a world that is in large part socially constructed. In particular, the meaning of objects, events, and behaviors comes from the interpretation people give them, and interpretations vary from one group to another. Cooley, in his theory of a "looking glass self," argued that the way we think about ourselves is particularly apt to be a reflection of other people's appraisals (or more accurately, our imagining of other people's appraisals) and that our self-concepts are built up in the intimate groups that he called "primary groups." Mead emphasized that human beings do not react directly to events; they act based on their interpretation of the meaning of events.
The words we use to describe our behavior and the behavior of others are particularly important, according to this theory. The new prostitute learns to denigrate the "square" world and admire people whose lifestyle reflects "the racket life." (Heyl)Another example is the rapist who insists that some women (hitch hikers for example) cannot be considered victims, because they are "asking for it." (Scully and Marollis).
Symbolic interactionists emphasize that deviants, like people who are more conformist, live in a world that is socially constructed. Certain identities are available and others not available; some behaviors get you prestige and respect while others are deprecated or punished, and the behaviors that are approved or punished may change dramatically over time.
I see differential association theory, neutralization theory, and labeling theory as subtheories that share many of the assumptions of symbolic interactionism.