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.