Health improvement requires collective as well as individual action, and the health of poor populations in particular requires collective action between countries as well as within them. Initiatives such as the Global Fund to Fight AIDS, Tuberculosis and Malaria reflect a growing awareness of this fact. However, initiating, organizing and financing collective actions for health at the global level presents a challenge to existing international organizations. The concept of "global public goods" (GPGs) suggests one possible framework for considering these issues. The central issue for health-related GPGs is how best to ensure that the collective action necessary for health is taken at the international level. The first large-scale study of the application of GPG finds that, while the concept has important limitations, for some areas of health work it can offer guidance in the financing and provision of global health programs.