Objective. To determine whether (a) quality in schizophrenia care varies by race/ ethnicity and over time and (b) these patterns differ across counties within states. Data Sources. Medicaid claims data from California, Florida, New York, and North Carolina during 2002-2008. Study Design. We studied black, Latino, and white Medicaid beneficiaries with schizophrenia. Hierarchical regression models, by state, quantified person and county effects of race/ethnicity and year on a composite quality measure, adjusting for personlevel characteristics. Principal Findings. Overall, our cohort included 164,014 person-years (41-61 percent non-whites), corresponding to 98,400 beneficiaries. Relative to whites, quality was lower for blacks in every state and also lower for Latinos except in North Carolina. Temporal improvements were observed in California and North Carolina only. Within each state, counties differed in quality and disparities. Between-county variation in the black disparity was larger than between-county variation in the Latino disparity in California, and smaller in North Carolina; Latino disparities did not vary by county in Florida. In every state, counties differed in annual changes in quality; by 2008, no county had narrowed the initial disparities. Conclusions. For Medicaid beneficiaries living in the same state, quality and disparities in schizophrenia care are influenced by county of residence for reasons beyond patients' characteristics.