Approximately one-third of the subjects reported histories of sexual abuse. The prevalence was 64 percent among females and 24 percent among males. A history of sexual abuse correlated with several social, behavioral, and psychological characteristics of individuals at entry to treatment. These characteristics included greater drug use, more severe psychopathology, family drug use, and more deviant peer associations. Cox regression analyses also revealed that a history of sexual abuse was related to earlier onset of alcohol and illicit drug use. One explanation of the findings is the self-medication hypothesis, which states that drug use functions to relieve feelings of depression and poor self-esteem, which often accompany victimization by child abuse. Tables and 36 references (Author abstract modified)