The EuroQol Group first met in Rotterdam in May 1987 determined to develop a standardised n-disease-specific instrument for valuing health-related quality of life. The book traces the activities of the Group over the next 25 years. The instrument constructed, eventually named the EQ-5D, was translated into many languages and used in a wide range of countries and settings. The book describes how the instrument's descriptive system was determined, how translation and language issues were handled, and how valuations were provided. Recent developments, in particular a 5-level version (EQ-5D-5L), and a youth version (EQ-5D-Y) are covered. The history of the institutional and administrative framework within which the Group operated is also treated.