This paper argues that shifts in the focus of human services – and, in particular, what counts as a successful outcome of such provision – reflect wider societal trends in values and concerns. The current ascendance of ‘quality of life’ (QoL) as a metric of service outcome is noted. The core functions of QoL assessments are identified and related to underlying qualities reflected in the majority of QoL assessments: comprehensiveness, context independence and the capability to reflect personal subjectivity. The attractiveness of these qualities is linked to current trends in philosophical thought, underpinning contemporary culture and social policy. It is proposed that the pre-eminence of QoL assessment as an approach to service planning and evaluation reflects the capacity of the QoL concept to accommodate tensions between modernist and postmodernist expectations, and serve as a basis for transparent resource allocation between competing priorities for restricted public spending. QoL may thus be seen as a successful ‘meme’ which has reproduced in a social and intellectual climate to which it is well adapted. The consequences of this for the use and abuse of QoL assessments within services for persons with intellectual disabilities are discussed and practical implications noted.