Follow-up studies of adolescent depression and conduct disorder have pointed to homotypic continuity, but less information exists about outcomes beyond mental disorders and about the extent to which adolescents with different disorders experience different versus similar difficulties during the transition to adulthood. We assessed the continuity of adolescent disorder by following girls in a complete birth cohort who at age 15 were depressed (n = 27), conduct disordered (n = 37), or without a mental health disorder (n = 341) into young adulthood (age 21) to identify their outcomes in three domains: mental health and illegal behavior, human capital, and relationship and family formation. We found homotypic continuity; in general, depressed girls became depressed women and conduct disordered girls developed antisocial personality disorder symptoms by age 21. Conduct disorder exclusively predicted at age 21: antisocial personality disorder, substance dependence, illegal behavior, dependence on multiple welfare sources, early home leaving, multiple cohabitation partners, and physical partner violence. Depression exclusively predicted depression at age 21. Examples of equifinality (where alternate pathways lead to the same outcome) surfaced, as both adolescent disorders predicted at age 21: anxiety disorder, multiple drug use, early school leaving, low school attainment, any cohabitation, pregnancy, and early child bearing.