The purpose of this study was to investigate the hypothesis that self-injurious behavior (SIB) maintained by environmental factors will be more effectively treated by behavioral treatments than by haloperidol. Fifteen subjects were enrolled in this study. The efficacy of both haloperidol and a behavioral treatment was assessed. At the onset of treatment, subjects were randomized to receive either haloperidol or a placebo. During each day of treatment, data were collected during sessions with a behavioral treatment and sessions without a behavioral treatment. Behavioral treatment resulted in a statistically significant decrease in SIB, but haloperidol did not. Eighty-three percent of subjects were classified as responders to the behavioral treatment whereas only 25% of the subjects were responders to haloperidol (p = .019). We conclude that individuals with operant SIB are more likely to respond to behavioral treatments than to haloperidol.