This study explores the impact of program structure on children's use of care by comparing care use in State Children's Health Insurance Program (SCHIP) and Medicaid covered populations in a State where children share the same provider network and are both in a primary care case management system with the same Medicaid fee structure. We then compare care use in this system to care use in an SCHIP structured as a fee-for-service (FFS) system using a private insurance provider network and fee schedule. Where SCHIP and Medicaid Programs share a primary care case management (PCCM) system, we find more use of well-child care among Medicaid covered children, but more use of office-based physician care among SCHIP covered children. Across the Medicaid PCCM-based and the private insurance FFS-based system, we find more use of primary and specialty care in the FFS system, and more use of well-child care and less use of emergency departments for non-urgent care in the PCCM-based system.