This study examines several methodologic issues in research on religion and health, including the measurement of the concept of religion, research designs, sampling, and statistical controls for assessing the "net" effects of religion on health outcomes. It briefly discusses differences in analytical perspectives that have contributed to the debate about the effects of religion on health. The authors review some of the methodologic problems of past research in this area of study and address what needs to be done to enhance the quality of the research. The authors conclude that the research methodology used in studies of religion and health has improved over time and that it continues to do so.