Prior research has shown that attention deficit/hyperactivity disorder (ADHD) relates to various negative outcomes in adolescence, including academic failure, behavioral problems at school, and criminal behavior. However, this line of research has generally failed to explore whether ADHD connects to criminal behavior through its effects on school factors. Using data from the National Longitudinal Study of Adolescent to Adult Health (Add Health), this study finds that a retrospective account of ADHD symptomatology during childhood and early adolescence predicts weakened school attachment, lower grades, and higher risks for both out-of-school suspension and crime. School attachment, grades, and out-of-school suspension have the expected effects on crime among females and males. Among females, these school factors mediate the effects of ADHD symptomatology on crime. The effect of ADHD symptomatology on crime among males remains significant when controlling for school factors. Implications of the findings for policy and theory are discussed.