Border R, et al. - Common and independent contributions to mortality hazard were examined in adolescents ascertained for conduct disorder (CD) and substance use disorder (SUD), their siblings and community controls. Researchers hypothesized that individual differences in CD and SUD severity would explain unique variation in mortality risk beyond that due to clinical/control status and demographic factors. Multi-site sample recruited in San Diego, California and Denver, Colorado, USA was analyzed for mortality in a prospective study (Genetics of Antisocial Drug Dependence Study) that began in 1993. Findings revealed a far greater risk of premature death among youth with conduct and substance use disorders and their siblings than demographically similar community controls. Conduct disorder, vs substance use disorder severity, is identified to be the robust predictor of unique variance in all-cause mortality hazard beyond other risk factors.