Numerous studies have examined the effects of severity and certainty of punishment on crime using official and self-report data. In general, these studies suffer from a variety of methodological problems, have produced mixed results, and indicate that other factors (e.g., demographics, perceptions, prior experience) influence decisions to engage in criminal activity. Similarly, studies of diversion programs aimed at preventing delinquency associated with labeling and stigmatization have shown little significant effect on criminal behavior. Counseling interventions also appear relatively ineffective, and some have produced negative effects. While behavior modification approaches show some promise, more research is needed. More success has been found in programs using environmental manipulations such as positive peer groups, remedial education, and preschool enrichment. 96 references.