Conduct disorder (CD) is associated with a number of adverse psychosocial outcomes in adulthood. There is consistent evidence that CD is predictive of antisocial behavior, but mixed evidence that CD is predictive of other externalizing and internalizing disorders. Further, externalizing and internalizing disorders are often associated with similar psychosocial outcomes as CD. However, relatively little work has examined whether forms of psychopathology (e.g., externalizing and/or internalizing disorders) mediates the relationship between youth CD and adult psychosocial outcomes. The present study examined associations between youth CD and adult psychosocial outcomes and sought to identify forms of psychopathology that may potentially mediate this relationship. Participants completed self-report measures of psychosocial functioning and semi-structured diagnostic interviews during adolescence and young adulthood. Analyses found that most domains of adult psychosocial functioning were associated with youth CD. Adult antisocial behavior was the only form of psychopathology predicted by CD. Adult antisocial behavior appeared to mediate the relationship between CD and marital status, life satisfaction, and being in jail and partially mediated the relationship between CD and family support and global functioning. These data suggest that reducing the progression to adult antisocial behavior may improve multiple psychosocial outcomes among those with a history of CD. (Contains 4 tables.)