This study investigated the relationship between age of onset of drug use and patterns of ensuing drug abuse for white, middle-class psychiatric patients, ranging in age from 15 to 25 years. The results for male patients show that the earlier the onset of drug use (ages 12 to 14), the greater the likelihood of becoming heavily involved with a variety of drugs, excepting heroin. Males who start using drugs after age 14 tend to become more involved with heroin use. For female patients, the earlier the age of onset of drug use, the more likely they are to become involved in all drugs, including heroin. Furthermore, for younger females (ages 12 to 14), drug use and promiscuity were both seen as manifestations of emotionally unstable, antisocial behavior.