Objective: Recently, behavioral scientists have developed greater interest in understanding the relations between religiousness and spirituality (R/S) and health. Our objectives were to (a) provide an overview of the R/S and health literature specific to cardiovascular disease (CVD) and cancer, (b) discuss the importance of religious culture considerations to behavioral medicine research, (c) suggest methodological changes to advance this research toward greater depth of understanding, and (d) begin discussion on clinically appropriate ways to integrate R/S into treatment. Method: Individual studies and meta-analyses on the relations of R/S with CVD and cancer were reviewed along with articles on the importance of culture to understanding R/S phenomena. Results: Trends in the literature suggest that R/S predicts reductions in all-cause and CVD-related but not cancer mortality. R/S also shows relations with cardiovascular morbidity, and various dimensions of R/S show relations with cancer risk factors and well-being in cancer patients. Investigators have progressively studied more specific dimensions of R/S but have largely failed to consider them within religious cultural contexts. This context is essential for a deeper understanding of R/S and health relations and has profound methodological implications for future studies. Conclusions: R/S and health research is expanding; yet, the field needs more programmatic research and greater theoretical organization. We propose that consideration of R/S variables within their religious culture will provide structure for greater integrative understanding to move the field forward. This understanding is imperative if R/S is to be appropriately integrated into culturally sensitive clinical interventions.