This book provides an overview of the research on spirituality, religiousness and health, including the most important studies, conceptualization, instruments for measurement, types of studies, challenges, and criticisms. It covers essential information on the influence of spirituality and religiousness (S/R) in mental and physical health, and provides guidance for its use in clinical practice. The book discusses the clinical implications of the research findings, including ethical issues, medical/health education, how to take a spiritual history, and challenges in addressing these issues, all based on studies showing the results of incorporating S/R in clinical practice. It contains case reports to facilitate learning, and suggests educational strategies to facilitate teaching S/R to health professionals and students.