This chapter presents a review of the research and theorizing about age and crime as depicted in control theory. It critiques psychological and sociological studies of the meaning of the age–crime relationship. It also discusses testing general theory when age is a direct cause of crime, methods of accounting for the age–crime relationship in criminology, and the value of typologies and statistical treatments of age and crime. The accumulated evidence from the best research supports the conclusion that statistical and theoretical models meant to account for the age effect in criminology lack empirical and methodological support. As a result, the best stance for criminology, in both theory and policy, is to assume a direct effect for age. Implications for juvenile justice and the role of age in separate systems for adults and juveniles are discussed.