Such a causal chain must also incorporate the biological and hormonal intermediaries between DNA and personality. In addition, Pavlovian conditioning appears to explain the specific behaviors that make up antisocial conduct. This theory suggests an interaction between social and psychophysiological factors and not a 100 percent biological chain of causation. A review of the empirical findings relating to these theories suggests a fairly definite framework, which also suggests some ways to reduce criminality. These findings suggest that modern correctional practices are usually the opposite of what psychology would recommend. Psychology suggests that at most one warning should be given at the first offense and that serious punishment should follow the next offense. Thus, the restricted usefulness of prison in rehabilitation is understandable as a consequence of earlier misplaced lenience. Psychological research also indicates that behavioral approaches based on learning theory are most effective and that traditional psychodynamic and nondirective client-centered therapies are ineffective. However, psychology suggests that criminality has many causes and that no single measure will have a large effect. The roles of school, prenatal factors, and perinatal factors also deserve further study. Figures, note, and 26 references