Ghana's health service delivery is characterized by inadequate institutions and lack of accountability. One of the reasons for the introduction of the National Health Insurance Scheme (NHIS) in Ghana was to facilitate citizen participation and ownership of the health service delivery system. Yet, this aspect of the scheme has often been overlooked. We examine how the NHIS and its related institutions perform the role of public oversight over frontline providers to ensure quality services. The main findings are: (i) there is improvement in the purchasing power of clients (policyholders use insurance card as a purchasing voucher to seek health care);(ii) competition among frontline providers generated by the National Health Insurance Authority's accreditation procedures ensures institutionalization of quality services for clients; and (iii) related institutions under the scheme, educate and mobilize the people and build up communal power which ensures that communities act jointly to demand quality services. We conclude that creating institutional space for direct participation of users and citizens in general is a robust means of concurrently empowering citizens and providing an avenue by which providers may be sanctioned, thus making them more responsive to users.