Demand side financing strategies have been a popular means of increasing coverage and availability of effective maternal and child health services in low and middle income countries (LMIC). However, most research to date has focused on the effects of demand side financing on the use and costs of care with less attention being paid to how they work to achieve outcomes. This study used a mixed methods evaluation to determine the effect of a targeted health insurance scheme on access to affordable quality maternal and child care, and assess implementation fidelity and how this affected programme outcomes. Programme effects on service access, affordability and quality were evaluated using difference in difference regression analysis, with outcomes being measured through facility, patient and household surveys and observations of care before the intervention started and eighteen months later. A simultaneous process evaluation was designed as a case study of the implementation experience. A total of 90 in-depth interviews (IDIs) and five focus group discussions were conducted during three rounds of data collection among respondents from management, facility and community. The scheme achieved high coverage among the target population and reduced the amount paid for antenatal and delivery care; however, there was no effect on service coverage and limited effects on quality of care. The lack of programme effects was partly due to the late timing of first antenatal care visits and registration for the scheme together with limited understanding of entitlements among beneficiaries and providers. Better communication of programme benefits is needed to enhance effects together with integration of such schemes within existing purchasing mechanisms and in financially decentralised health systems.