In an effort to develop a patient questionnaire with sufficient validity and reliability to be used to measure patient perceptions of quality, over 30,000 patients from 178 solo and group practices completed the Physician Office Quality of Care Monitor (QCM). The study found strong evidence of construct validity, predictive validity, and internal consistency for the questionnaire. Physician interactions were the most important aspect of office care while coordination of care over time was found to be the best issue to differentiate patients likely to recommend a practice from those less likely to recommend. An inverse relationship was found between practice size and patient satisfaction. Health maintenance organization (HMO) patients reported lower satisfaction, as did younger patients.