The present study assessed the mental health and criminal records of 6,449 males and 6,268 females who presented conduct problems as children by examining an unselected birth cohort followed up to age 30. Conduct problems were defined by teacher ratings of behavior problems and/or antisocial behavior in the community. There was little overlap in the children identified by teachers and by the community. These two groups of children were at differential risk for adult mental disorder. Seventy-six percent of the males and 30% of females with childhood conduct problems had either a criminal record, a mental disorder, or both by age 30. Risk ratios for adult criminality and/or mental disorders, however, were greater for females than for males with a history of childhood conduct problems. Almost all of the mental disorders were severe substance abuse. Mental disorders and crime were strongly associated among males with a history of childhood conduct problems.