This study investigated whether drug dealing juvenile offenders in Belgium differ from non-drug dealers in levels of violent and non-violent offending behaviors, aggression, substance use, and mental health needs. The current study examined data from 226 16- to 17-year-old male juvenile offenders. Information relating to drug dealing, substance use, and mental health needs were collected through self-report questionnaires. A structured diagnostic interview was used to collect information about past violent and non-violent behaviors. Chi-square tests and multivariate analysis of variance compared non-dealers and dealers and explored if hard-drug dealers and soft-drug dealers differed from each other. Relative to non-drug dealers, drug dealers engaged in more violent offending behaviors, exhibited higher levels of aggression, substance use and oppositional defiant problems, and displayed lower levels of anxiety. Soft- and hard-drug dealers did not differ from each other. To conclude, detained drug dealers are characterized by severe antisocial behavior.