Results of the study indicate that young adult amphetamine users were more likely to have concurrent symptoms of mental illness and problem behaviors and to use or abuse cigarettes, cannabis, or other illicit drugs. In multivariate analyses, young adults’ amphetamine use and disorder were disproportionately more common among males and those who had prospectively reported aggression/delinquency or smoking at 14 years of age, or who had experienced childhood sexual abuse. The findings from the study suggest that problem behaviors, smoking, and childhood sexual abuse are predictors of initiation to use of amphetamines and development of amphetamine abuse and dependence. Understanding the risk factors that predict amphetamine use and development of amphetamine abuse or dependence (disorder) may help guide preventive interventions. This study used data from a 21-year followup of a pre-birth cohort to examine: (1) correlates of amphetamine use and disorders in young adults, (2) early-life predictors of young adults’ amphetamine use and disorders, and (3) what proportion of variation in young adult's amphetamine use and disorders was associated with early-life risk factors. Tables and references