“Quality of life” has since a long time been an expression à la mode. It is much used in the public debate and it is influential in the field of?commerce. It has been claimed that this or that measure or this or that product will enhance our quality of life. But “quality of life” has also?become a technical term in social science and medicine. One can ask: what lies behind this development? And how comes that quality of life has become a technical concept also in scientific research?