Decreased success at work and educational attainment by adulthood are of concern for children with ADHD given their widely documented academic difficulties; however there are few studies that have examined this empirically and even fewer that have studied predictors and individual variability of these outcomes. The current study compares young adults with and without a childhood diagnosis of ADHD on educational and occupational outcomes and the predictors of these outcomes. Participants were from the Pittsburgh ADHD Longitudinal Study (PALS), a prospective study with yearly data collection. Significant group differences were found for nearly all variables such that educational and occupational attainment was lower for adults with compared to adults without histories of childhood ADHD. Despite the mean difference, educational functioning was wide-ranging. High school academic achievement significantly predicted enrollment in post-high school education and academic and disciplinary problems mediated the relationship between childhood ADHD and post-high school education. Interestingly, ADHD diagnosis and disciplinary problems negatively predicted occupational status while enrollment in post-high school education was a positive predictor. Job loss was positively predicted by a higher rate of academic problems and diagnosis of ADHD. This study supports the need for interventions that target the child and adolescent predictors of later educational and occupational outcomes in addition to continuing treatment of ADHD in young adulthood targeting developmentally appropriate milestones, such as completing post-high school education and gaining and maintaining stable employment.