The study examined associations between antisocial behavior (ASB) before age 15 and eight adverse outcomes from age 21 to 50 among 1,623 men and 324 women who as adolescents consulted a clinic for substance misuse problems. Outcomes were documented using Swedish national registers and included death, hospitalization for physical illnesses related to substance misuse, mental illness, self-inflicted harm, substance misuse, convictions for violent and nonviolent crimes, and poverty. ASB before age 15 was associated with increased odds of all outcomes in adulthood except hospitalization for mental illness after adjusting for low family socioeconomic status, sex, Sex × ASB, and substance misuse in adulthood and with an increased number of adverse outcomes up to age 50. No gender differences were detected.