Background: We examined racial/ethnic disparities in school-based behavioral health service use for children with psychiatric disorders. Methods: Medicaid claims data were used to compare the behavioral healthcare service use of 23,601 children aged 5-17 years by psychiatric disorder (autism, attention deficit hyperactivity disorder [ADHD], conduct/oppositional defiant disorder, and "other") and by race/ethnicity (African-American, Hispanic, white, and other). Logistic and generalized linear regression analyses were used. Results: Differences in service use by racial/ethnic group were identified within and across diagnostic groups, both for in-school service use and out-of-school service use. For all disorders, Hispanic children had significantly lower use of in-school services than white children. Among children with ADHD, African-American children were less likely to receive in-school services than white children; however, there were no differences in adjusted annual mean Medicaid expenditures for in-school services by race/ethnicity or psychiatric disorders. Statistically significant differences by race/ethnicity were found for out-of-school service use for children with ADHD and other psychiatric disorders. There were significant differences by race/ethnicity in out-of-school service use for each diagnostic group. Conclusions: Differences in the use of school-based behavioral health services by racial and ethnic groups suggest the need for culturally appropriate outreach and tailoring of services to improve service utilization.