Using a large sample of men, we examine alternative models of the way in which testosterone may influence adult deviant behavior. The results indicate a significant and moderately strong relationship between testosterone and adult deviance, and this relationship between testosterone and adult deviance is largely mediated by the influence of testosterone on social integration and on prior involvement in juvenile delinquency. In addition, testosterone level moderates the relationship of social integration to adult deviance: The restraining influence of social integration is less necessary for men with lower levels of testosterone. Further, prior delinquency interacts with social integration in the same fashion, accounting for much of the moderating effect of testosterone. This pattern of results supports the conclusions that (1) testosterone is one of a larger constellation of factors contributing to a general latent propensity toward deviance and (2) the influence of testosterone on adult deviance is closely tied to social factors. Our findings show that there is considerable promise in a biosocial approach that integrates social and biological explanations, rather than playing them off against one another.