This study evaluated predictors of adolescent delinquency severity (11 to 17 years of age) among a diverse group of preadolescent boys with attention deficit hyperactivity disorder (ADHD; n=100) and age-matched comparison boys (n=75). During childhood, baseline assessments yielded diagnostic information, and naturalistic summer programs provided multimethod measures of overt aggression, covert antisocial behavior (ASB), and peer status. Five years later, multi-informant measures of ASB and delinquency were gathered and independently rated. Baseline ADHD, overt aggression, and peer status were not significantly related to adolescent delinquency severity. Observed noncompliance and an objective measure of covert ASB each independently predicted delinquency. Covert ASB predicted delinquency severity more strongly for comparison boys than for probands.