The concept of quality of life (QOL) has become a measurable construct of great value to all people, including people with intellectual and developmental disabilities (IDD). In particular, the field of IDD is currently experiencing a paradigm shift related to beliefs, assumptions, policies, and practices concerning people with disabilities and their families and the place and role they play in society. This article starts by reconstructing the state of the art of the application of QOL in Social Services, reconstructing its research developments, operational declinations and influences in social policies in Spain and Italy.