Developmental cascades: linking adolescent substance use, affiliation with substance use promoting peers, and academic achievement to adult substance use disorders. Using a high-risk community sample (N = 405), the current study examined developmental cascades among substance use, affiliation with substance use promoting peers, and academic achievement over an 18-year period and tested whether these pathways mediated the influence of parental alcoholism on adult alcohol and drug use disorders. Results showed that the influence of parental alcoholism on adult drug disorders was mediated by developmental cascades across all three domains, whereas the influence of parental alcoholism on adult alcohol disorders was mediated through affiliation with substance use promoting peers and persistence in binge drinking. Adolescent drug use had more implications for adult outcomes than did adolescent alcohol use, which was less likely to spill over into other domains of functioning. Findings indicated that adolescent risk factors had indirect rather than unique effects on adult substance use disorders, suggesting that adolescent risk is not immutable and is largely mediated by later influences.