The current report introduces the Psychosocial Adjustment to Illness Scale (PAIS) and its self-report version the PAIS-SR. The PAIS is a multi-dimensional, semi-structured clinical interview designed to assess the psychological and social adjustment of medical patients, or members of their immediate families, to the patient's illness. The report reviews and discusses the concepts that form the foundation for the development of the PAIS. In terms of psychometric characteristics, both internal consistency and interrater reliabilities are presented and a series of predictive and convergent validity studies are reviewed. Six normative illness groups are described and discussed, and contributions to construct validity for the scale from factor analytic and other studies of internal structure are presented.