This paper describes the development of a Quality of Care and Support (QOCS) scale for use with adult persons with physical and intellectual disabilities. In the pilot phase of the study, 12 centers from around the world carried out focus groups with people with physical and disabilities, their carers, and with professionals in order to identify themes that were relevant for their quality of care. Items generated from the focus groups were then tested in a pilot study with 1400 respondents from 15 different centers worldwide, with items being tested and reduced using both classical and modern psychometric methods. A field trial study was then carried out with 3772 respondents, again with the use of both classical and modern psychometric methods. The outcome of the two rounds of data collection and analysis is a 17-item module for assessment of quality of care in physically or intellectually disabled people. Further modifications are also proposed for the use of the QOCS with adults with intellectual disabilities, including simplification of wording of some of the items, the use of a three-point response scale, and the inclusion of smiley faces.