Quality of life has become a dominant theme in planning and evaluating services for people with disabilities. This article reviews definitions of quality of life, explores the concept from the perspective of the optimal theory of personal well-being, and surveys the research on the concept and its implications for planning and evaluating services. This article explores the subjective nature of life quality, particularly for people with disabilities, and relates the concept to both cultural norms and universal human values and needs. Each person experiences life, and disability, in unique ways. Practitioners need to consider quality-of-life issues as a context in planning and evaluating quality services.