We compared perceptions about the practice environment and the job satisfaction of physician assistants (PAs), nurse practitioners (NPs), and primary care physicians in a large group-model HMO. The data source was a self-administered mail survey (average response rate = 79%). PA/NPs and primary care physicians reported that professional autonomy was not a problem and were satisfied with most aspects of practice in this setting. Common areas of dissatisfaction included patient load and amount of time with patients. PA/NPs were more likely than the physicians to experience stress on a daily basis, however, and were less likely to report that they would choose the practice setting again. They also were significantly less satisfied than the physicians with their incomes and fringe benefits. Our findings suggest that more attention should be given to practice conditions and compensation of PAs and NPs in managed care.