Objective:Describe the pre‐ and postinjury patterns of alcohol and other drug use among persons who have incurred traumatic brain injury (TBI). Injury‐related characteristics and negative consequences are also reported, as well as preliminary outcomes of treatment.Design:Descriptive analysis of a consecutive sample of persons referred during an 18‐month period to a treatment program for substance abuse after TBI.Setting:A community‐based demonstration project affiliated with an acute rehabilitation hospital in a large midwestern academic medical center.Patients:The first 211 persons screened by the program, including all 97 receiving comprehensive assessments and 68 who dropped out prior to assessment. Preliminary outcomes were based on the first 37 clients monitored 6 months after entering into treatment.Intervention:Screening for appropriateness of referral; comprehensive, holistic assessment; and resource and service coordination provided by an interdisciplinary staff that facilitates treatment by local providers.Main Outcome Measures:Alcohol use measured by the Quantity‐Frequency‐Variability Index, completed by client and significant other; productivity measured by the Employability Rating Scale; multiple sociodemographic indicators.Results:More than 60% of injuries were use related; this included 71% of assaults. Alcohol was the preferred drug for 83%, and more than half used some marijuana. Prior to injury, the study sample consumed significantly greater amounts of alcohol than national averages; after injury, consumption was consistent with national averages. Approximately 20% of individuals who abstained or were light drinkers before injury showed high volume use after injury.Conclusions:There are multiple reasons why the harmful effects of alcohol and other drug use after TBI are underestimated, including cultural acceptance of beer and the subtle sequelae of marijuana use. It is recommended that the extent of use of same‐aged peers not be used as the criterion for acceptable use by persons who have experienced TBI. Further study is needed regarding the utility of assessment devices, the effectiveness of referrals made during rehabilitation, and the efficacy of intervention techniques.