Many theories in criminology and the sociology of deviance propose why people engage in deviance. Social control theory tackles the reverse: Why don't people engage in deviance? From this angle, the assumption is that deviance from the norms of society is inherently attractive. What remains to be explained is why so many people don't follow this attraction.
Social control theory proposes that people have stakes in conformity—things that they value (e.g. health, wealth, love, friendship, respect) and keep/pursue only by conforming to some norm(s). People, then, are disinclined to deviate from the norms that sustain those stakes. In other words, people don't tend to engage in deviance that would threaten their stakes in conformity. Conversely, people with little to lose by breaking a norm tend to do so.
What does this imply about society? It implies that higher crime rates are found in areas where the populace lack stakes in conformity, and vice versa. It implies that the way to decrease crime rates is to give criminals a reason to conform—home ownership, a job, involvement in the community.
This is a paraphrasing of the description of social control theory found in the 8th edition of Erich Goode's Deviant Behavior (2008).