The past three decades have witnessed a surge in research on spirituality and health. This growing body of literature has linked many aspects of spirituality as well as religion to both positive and negative indices of human functioning. However, studies have primarily been descriptive, focusing on identifying associations between spirituality and health, rather than explanatory, focusing on identifying mechanisms underlying observed relationships. Earlier research is also limited by failure to control for salient covariates, apply prospective design, and use sophisticated measurements with well defined and empirically-validated factors. Recent research, however, is advancing the study of spirituality and health by examining not only whether religious factors are relevant to human health, but also how spirituality may functionally impact medical and psychological wellbeing and illness. This article introduces a special issue on Spirituality and Health containing 12 full-length research reports to further this welcomed, emerging trend.