Objective: The purpose of the present study was to examine the cross-ethnic construct validity of the Brief Symptom Inventory (BSI). Method: The sample consisted of 1,166 individuals diagnosed with severe and persistent mental illness who were receiving treatment in community-based mental health programs. Multiple-group confirmatory factor analysis was used to test measurement invariance of the BSI's second-order factor model across three ethnic groups (African Americans, Caucasians, and Latinos). Results: The data supported the configural invariance of the BSI's second-order factor model as well as the full metric invariance and the partial metric invariance. Conclusions: The present study presented substantial empirical evidence for the construct validity of the BSI's second-order factor model across the three ethnic groups. (Contains 3 tables and 1 figure.)