This study examined the developmental associations between substance use and violence.We examined the trends in each behavior throughout adolescence, how the behaviors covariedover time, and the symmetry of associations taking into account frequency and severity of eachbehavior. We also examined whether changes in one behavior affected changes in the otherbehavior over time. Six years of annual data were analyzed for 506 boys who were in the seventhgrade at the first assessment. Concurrent associations between frequency of substance use andviolence were relatively strong throughout adolescence and were somewhat stronger formarijuana than alcohol, especially in early adolescence. Type or severity of violence was notrelated to concurrent alcohol or marijuana frequency, but severity of drug use was related toconcurrent violence frequency. Depending, to some degree, on the age of the subjects, thelongitudinal relationships between substance use and violence were reciprocal duringadolescence and slightly stronger for alcohol and violence than for marijuana and violence.Further, increases in alcohol use were related to increases in violence; however, when earlyalcohol use was controlled, increases in marijuana use were not related to increases in violence.Only in early adolescence was the longitudinal relationship between marijuana use and laterviolence especially strong. The strength of the longitudinal associations between violence andsubstance use did not change when common risk factors for violence and substance use werecontrolled. Overall, the data lend more support for a reciprocal than for a unidirectionalassociation between substance use and violence. Prevention efforts should be directed ataggressive males who are multiple-substance users in early adolescence.