This quasi-experimental study examined the impact of a statewide integrated special needs program Health and Recovery Plan (HARP) for individuals with serious mental illness and identified racial and ethnic disparities in access to Medicaid services. Generalized estimating equation negative binomial models were used to estimate changes in service use, difference-in-differences, and difference-in-difference-in-differences in the pre- to post-HARP periods. Implementation of the special needs plan contributed to reductions in racial/ethnic disparities in access and utilization. Notable among those enrolled in the special needs plan was the declining Black–White disparities in emergency room (ER) visits and inpatient stays, but the disparity in non-behavioral health clinic visits remains. Also, the decline of Hispanic–White disparities in ER, inpatient, and clinic use was more evident for HARP-enrolled patients. Health equity policies are needed in the delivery of care to linguistically and culturally disadvantaged Medicaid beneficiaries.