This proposal describes an impact evaluation of the SKY Health Insurance Program in Cambodia. The origins of SKY (Sokapheap Krousar Yeung, “Health for Our Families”) lie in a microfinance program launched by Groupe d'échange et de recherche technologiques (GRET) in Cambodia in 1991. Observing that borrowers frequently cited health problems as a reason for dropping out of the program, GRET began to develop a micro-insurance product aimed at mitigating the disastrous consequences of health shocks. Piloted in 1998 and expanded in subsequent years, SKY offers households, for a fixed monthly premium, free and unlimited primary and emergency care at contracted health centers, as well as a number of other health services. One of SKY’s primary goals is to enable families to cover health costs without risking impoverishment. SKY typically represents the only health insurance option available in the regions where it operates.