The current paper provides background to the development of the Multidimensional Inventory for Religious/Spiritual Well-being and then summarises findings derived from its use with other measures of health and personality. There is substantial evidence for religiosity/spirituality being positively related to a variety of indicators of mental health, including subjective well-being and personality dimensions. Furthermore, religiosity/spirituality can play an important role in the process of recovering from mental illness as well as providing a protective function against addictive or suicidal behaviours. However, further research is needed to examine the mechanisms through which religiosity/spirituality have an impact on health-related conditions.