The authors examined whether substance use disorder (SUD) before age 19 was associated with functioning at age 30. Participants (N = 773) were assessed twice during adolescence and at ages 24 and 30. Eight of 14 adult measures were associated with adolescent SUD: education, unemployment, income, risky sexual behavior, suicide attempt, coping, stressful life events, and global adjustment. After adolescent comorbidity and functioning and adult SUD were controlled for, education and unemployment remained associated, and three variables emerged as significant: being a parent (significant only for participants without adult SUD), being currently married, and having decreased life satisfaction (significant only for participants with adult SUD). Adolescent SUD is associated with numerous functioning difficulties at age 30, some of which appear to be related to recurrent SUD, comorbid adolescent disorders, or functioning problems already evident in adolescence.