Objectives: The Brief Symptom Inventory (BSI) is widely used in juvenile justice settings; however, little is known regarding its factor structure in antisocial youth. The authors evaluated the BSI factor structure in a state residential treatment population. Methods: 707 adolescents completed the BSI. Exploratory and confirmatory factor analyses were used to assess factor structure. Intergroup variability was examined using multiple-group structural equation modeling. Results: Findings supported a 6-factor, 25-item model explaining 49.5%of sample variance. The derived structure differed from prior findings with adult psychiatric patients by including a suicidal ideation latent variable and excluding several developmentally inappropriate factors. Conclusion: There may be problems associated with indiscriminant application of the original BSI factor model to juvenile justice populations. (Contains 5 tables.)