Background: The purpose of this study was to examine whether Latino patients presenting for behavioral health treatment showed major systematic differences in presenting symptoms, clinical severity, and psychiatric diagnosis compared with European American and African American patients. Documenting such differences should have important implications for evidence-based clinical practice. Methods: Data were drawn from a large behavioral health service delivery system in New Jersey, and included administrative data, clinical diagnosis, a clinician-rated global level of functioning, and a self-reported symptoms and functioning scale. The study involved a clinical sample of all new admissions into the system between January 1, 2000, and August 31, 2001. To examine the main effects of ethnicity, in the context of other independent variables, logistic regression was performed for each of 3 dependent binary variables: presence or absence of major depression, a schizophrenia spectrum disorder, and bipolar disorder. Results: Consistent with previous studies, we found that African Americans were diagnosed as having a disorder SERVICE USE AND DIAGNOSTIC DISPARITIES Public policy considerations and standards of care require that all ethnic groups have access to behavioral health care, and that the same criteria are applied to their diagnostic assessment and treatment. However, prior research has revealed differential use patterns and diagnostic disparities in African Americans. Based at least on anecdotal information, it has been suggested that Latinos also share these disparities. Evidence regarding patterns of use, diagnosis, and self-reported symptom severity by Latinos has been scant and sometimes conflicting. Recent research 2,3 documents that African Americans and Latinos are underrepresented in mental health service systems across the nation, compared with European Americans. While epidemiological studies 4-7 show that individuals in the general population are not likely to receive mental health treatment even when