The increased use of managed care in Medicaid warrants examination of any differential effects on care receipt by racial and ethnic minority populations. This paper explores such effects on preventive care use by children ages three through six years and adolescents ages 12 through 17. Enrollment, claims, and encounter data from the Maryland Medicaid program were analyzed. The period of study includes 1997, the year preceding the implementation of managed care, and two post implementation years, 2001 and 2004. Bivariate analyses establish patterns of use across racial and ethnic groups and trends over time. Difference-in-difference regression estimates the differential effects of managed care by race and ethnicity. Controlling for demographic and program characteristics, no disparities were observed prior to managed care. Under managed care, the probability of service receipt was increased for all but White adolescents. Black and Hispanic children and adolescents experienced greater gains than their White peers.