From a concept to a theory: The six eras of quality of life research and application

This article describes the evolution of the quality of life concept through the lens of six distinct eras. Each era reflects a shared process in which multiple stakeholders, including persons with intellectual and developmental disabilities and researchers, have played a significant role. Across these six eras, research on quality of life has evolved from operationalizing a concept to developing a theory. As described in the article, the first three eras resulted in formulating conceptualization, measurement, and application principles; developing quality of life conceptual and operational models; and constructing reliable and valid instruments to assess quality of life domains or domain-referenced indicators. The application era has focused on applying the concept of quality of life and its measurement, supports provision, conceptualization and theory, and systemic change. The final two eras have involved theory development and theory confirmation. •Evolution of conceptualization, measurement and application principles on the concept of quality of life.•Mediating and moderating factors that influence quality of life.•Theory definition and model development of quality of life.•Quality of life enhancement strategies and focus areas.•Quality of life theory-based hypotheses.