OBJECTIVE To describe the relative importance of factors influencing pediatricians' participation in Medicaid in North Carolina. METHODS Questionnaire survey. METHODS Nonacademic primary care pediatricians in direct patient care at least 50% of the time; 332 (85%) of the 389 eligible pediatricians responded. METHODS Proportion of pediatricians who restricted Medicaid patients' access to their practices. The association between restricting access and the following factors was assessed: Medicaid reimbursement, pediatricians' demographic characteristics, knowledge of the Medicaid program, attitudes toward Medicaid patients and the Medicaid program, and beliefs about whether other physicians were available to care for Medicaid patients. RESULTS Twenty-nine percent of pediatricians restricted Medicaid patients' access to their practices. The proportion of pediatricians restricting access was 62% in cities, 13% in medium-sized towns, and 12% in small towns (P less than .001), but the proportion of pediatricians in cities who restricted access varied from 87% to 22%. Pediatricians who received a higher proportion of their usual fee were less likely to restrict Medicaid patients' access. The relationship between Medicaid payment and restricted access was substantially weakened after controlling for the following factors: (1) the size of the community, (2) pediatricians' attitudes toward Medicaid payment, (3) their perceptions that they were too busy to care for Medicaid patients, and (4) whether there were other resources for the care of Medicaid patients. At comparable levels of payment, rural pediatricians were about six times less likely than urban pediatricians to restrict access. Pediatricians who knew less about Medicaid reimbursement also restricted access more often. Whether or not they restricted access to new Medicaid patients, pediatricians provided acute, preventive, hospital, and emergency care to the Medicaid patients who were already in their practices. CONCLUSIONS Existing resources for the care of Medicaid patients, pediatricians' economic dependence on Medicaid, and the local norms of practice may be important factors in pediatricians' decision to participate in Medicaid. Increasing reimbursement will have only modest effects on Medicaid participation. Strategies to improve participation should also address pediatricians' knowledge of the Medicaid program and enlist the support of community physicians.