The Southwest Oncology Group Quality of Life Questionnaire is based on six policy recommendations adopted by the Group: 1. Always measure physical functioning, emotional functioning, symptoms, and global quality of life separately. 2. Include measures of social functioning and additional protocol-specific measures if resources permit. 3. Use patient-based questionnaires. 4. Use categorical rather than visual analogue scales. 5. Select brief questionnaires (not interviews). 6. Select quality of life measures with published psychometric properties. Three additional policy recommendations deal with procedures and issues associated with the assessment of quality of life in a Southwest Oncology Group prostate cancer trial. Communication among investigators and groups can improve access to newly developed QOL measures and assure consistent quality control procedures across cooperative group trials.