This paper reviews recent results and work in progress from a longitudinal study of drug use etiologies and consequences. Early- and mid-adolescent drug use patterns, personality, and behavioral correlates were studies in a large sample of normal youth beginning in the mid-1970's. To determine the correlates and consequences of adolescent drug use, controlling for related tendencies such as lack of social conformity and deviat friendship networks, 654 youngsters were folled into young adulthood and their behaviors and lifestyles evaluated. Teenage drug use was found to disrupt many critical developmental tasks of adolesence and young adulthood. Tendencies to use many different drugs as an adolescent led in young adulthood to increased drug crime involvement, decreased college involvement, increased job instability, income, psychotism, and stealing episodes. Intervention efforts should be directed not only towards decreasing drug use, but also towards improving personal maturity, social skills, and economi...