Data from the 1986 Northern Finland Birth Cohort Study (n = 4,645) were used to examine the influence of mid-adolescent (age 15) school outcomes on late-adolescent (ages 17-19) risk of criminal conviction. Consistent with social-developmental theories of offending, we found that poor academic performance and reduced school attachment increase the risk of criminal conviction independently of pre-existing differences in antisocial propensity and other confounding factors identified in prior research. Moreover, in support of an integrated model, our research suggests that academic performance and school attachment mediate the effects of childhood antisociality and learning difficulties on late-adolescent risk of criminal conviction. The implications of findings for policy and future research are discussed.