The cultural equivalence of psychological outcome measures remains a major area of investigation. The current study sought to test the factor structure and factorial invariance of the Brief Symptom Inventory-18 (BSI-18) with a sample of adult individuals of Mexican descent (N = 923) across nativity status (U.S.- vs. foreign-born), language format (English vs. Spanish), and gender. The results show that 1-factor and 3-factor measurement models provided a good fit to the data; however, a single-factor model was deemed more appropriate and parsimonious. Tests of measurement invariance and invariance of factor variances (i.e., structural invariance) indicated at least partial measurement invariance across gender, nativity status, and language format. These findings suggest that the BSI-18 operates in a similar fashion among adults of Mexican descent regardless of nativity status, language format of the survey, and gender. Clinical and practical implications for use of the BSI-18 with Latino populations are discussed. (Contains 1 table.)