This paper reports on the field testing, empirical derivation and psychometric properties of the World Health Organisation Quality of Life assessment (the WHOQOL). The steps are presented from the development of the initial pilot version of the instrument to the field trial version, the so-called WHOQOL-100. The instrument has been developed collaboratively in a number of centres in diverse cultural settings over several years; data are presented on the performance of the instrument in 15 different settings worldwide.