Severe brain injury can result in significant neurobehavioral and social functioning impairment. In rehabilitation settings, behavioral problems of aggression and nonadherence to therapeutic activities can pose barriers to maximal recovery of function. Behavioral interventions seem to be effective in reducing problem behavior among individuals recovering from severe brain trauma, but well-controlled studies examining the efficacy of such interventions are sparse. This article presents a single-case, multiple-baseline study of a differential reinforcement of other behavior (DRO) procedure in a 28-year-old, brain-injured male with aggressive behavior problems. The procedure successfully reduced the frequency of problem behavior by up to 74%, maintained at 1-month follow-up. Implications of this intervention for individuals with brain injury are discussed, and testing of this procedure using a between-group design seems indicated.