The 2001 (first) edition of this Handbook was a comprehensive review of history, research, and discussions on religion and health through the year 2000. The Appendix listed 1,200 separate quantitative studies on religion and health each rated in quality on 0–10 scale, followed by about 2,000 references and an extensive index for rapid topic identification. The 2012 (second) edition of the Handbook systematically updated the research from 2000 to 2010, with the number of quantitative studies then reaching the thousands. This 2023 (third) edition is the most scientifically rigorous edition to date, covering the best research published through 2021 with an emphasis on prospective studies and randomized controlled trials. Beginning with a Foreword by Dr. Howard K. Koh, former US Assistant Secretary for Health for the Department of Health and Human Services, this nearly 600,000-word volume examines almost every aspect of health, reviewing past and more recent research on the relationship between religion and health outcomes. Furthermore, nearly all of its 34 chapters conclude with clinical and community applications, making this text relevant to both healthcare professionals (physicians, nurses, social workers, rehabilitation therapists, counselors, psychologists, sociologists, etc.) and clergy (community clergy, chaplains, pastoral counselors, etc.). The book’s extensive Appendix focuses on the best studies, describing each study in a single line, allowing researchers to quickly locate the existing research. It should not be surprising that for the past two decades the Handbook has been the most cited of all references on religion and health.