Public-private partnerships have become a common approach to health care problems worldwide. Many public-private partnerships were created during the late 1990s, but most were focused on specific diseases such as HIV/AIDS, tuberculosis, and malaria. Recently there has been enthusiasm for using public-private partnerships to improve the delivery of health and welfare services for a wider range of health problems, especially in developing countries. The success of public-private partnerships in this context appears to be mixed, and few data are available to evaluate their effectiveness. This analysis provides an overview of the history of health-related public-private partnerships during the past 20 years and describes a research protocol commissioned by the World Health Organization to evaluate the effectiveness of public-private partnerships in a research context.