This paper describes the World Health Organization's project to develop a quality of life instrument (the WHOQOL). It outlines the reasons that the project was undertaken, the thinking that underlies the project, the method that has been followed in its development and the current status of the project. The WHOQOL assesses individuals' perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns. It has been developed collaboratively in several culturally diverse centres over four years. Piloting of the WHOQOL on some 4500 respondents in 15 cultural settings has been completed. On the basis of this data the revised WHOQOL Field Trial Form has been finalized, and field testing is currently in progress. The WHOQOL produces a multi-dimensional profile of scores across six domains and 24 sub-domains of quality of life.