Associations between the extent of conduct problems at age 8 years and later life opportunity outcomes at age 18 years were examined in a birth cohort of New Zealand children studied prospectively to age 18 years. Conduct problems at age 8 were assessed using a combination of parent and teacher reports of conduct disordered and oppositional behaviours. Two measures of life opportunities were assessed at age 18: (a) whether the young person had left school by age 18 without educational qualifications; (b) whether the young person had experienced a period of unemployment of 3 months or longer following school leaving. The analysis suggested the following conclusions: (1) There were clear and significant (p<.0001) tendencies for increasing levels of conduct problems at age 8 to be associated with increasing risks of leaving school without qualifications and of unemployment by age 18. (2) A substantial component of these associations was explained by a series of confounding social, family, and individual factors (notably child intelligence, early attentional problems, and family sociodemographic disadvantage) that were associated with both early conduct problems and later life opportunities. (3) Further analysis suggested that linkages between early conduct problems and later educational underattainment and unemployment (after adjustment for confounders) were mediated by a series of adolescent behavioural processes including patterns of peer affiliations, substance use, truancy, and problems with school authority.