This chapter distinguishes between the concepts of religion and spirituality. It provides a brief summary of the empirical evidence relating religious and spiritual (RS) issues to health provides a foundation for an articulation of what psychotherapists consider to be the two primary rationales for integrating RS issues into psychological treatment. To accomplish the goal, the chapter provides a brief introduction to RS-oriented assessment and intervention strategies. Religion can be viewed as a social institution that encourages people to observe a system of beliefs, practices, rituals, and symbols. Besides being associated with mental health and illness, RS issues may be important to the treatment process or therapeutic relationship. The professional value of cultural sensitivity and inclusion also supports the integration of RS issues in psychological treatment. Only Propst and Propst have found a religiously adapted cognitive behavioural therapy approach to be more effective in reducing depression with religious clients than a secular version.