A total of 400 randomly selected adult residents of a metropolitan community in the Southwest were interviewed concerning past and future violations in eight illegal behaviors: theft ($20 or more), illegal gambling, tax cheating, theft (less than $20), hurting someone, littering, illegal fireworks, and drunk driving. Their responses were correlated with three independent variables: perceived certainty and severity of punishment and moral commitment. Controlling for the additive effects and first-order interactions, the study found that the combination of low moral commitment, high peceived certainty, and high perceived severity leads to low involvement in illegal behavior. Yet many of those who are morally committed to a legal norm have violated it in the past and believe they probably will in the future. Thus, legal sanction threat is not a residual, secondary factor in deterrence and should have a more central place in sociological theories of social control. Tabular data and over 30 references are provided.