A review of quantitative research studies published between 1991 and 1995 in 3 major mental health nursing journals revealed that approximately 10% (31 of 311) included a measure of religion or spirituality. This percentage (10%) is 3 to 8 times higher than that found in previous reviews of empirical research in psychological and psychiatric journals, suggesting that mental health nursing research is more sensitive to the role of religious-spiritual factors on mental health than research in related disciplines. The results are discussed in the context of the history and philosophy of nursing and in comparison to related disciplines. Methodological aspects of the research, especially the importance of multiple measures, are discussed, as are other salient findings.