As the nation once again engages in discussions of health reform, issues of quality and cost containment are high on the agenda. One approach to addressing these challenges is team-based delivery of health care services, including physicians and allied health professionals working collaboratively. The imperative to consider team-based care is fueled by the unrelenting escalation in health care costs in the care of the chronically ill covered by Medicare; in the error-prone features of the current fragmented delivery system; and by the shortage of primary care physicians. In 2003, the Institute of Medicine (IOM) recommended that “all health professionals should be educated to deliver patient-centered care as members of an interdisciplinary team, emphasizing evidence-based practice, quality improvement approaches, and informatics.”1 In 2007, the American Academy of Family Physicians, the American Academy of Pediatrics, the American College of Physicians, and the American Osteopathic Association developed the concept of a physician-led, medical home model in which primary care physicians assume the responsibility of coordinating chronic care management for adult patients across settings using a patient-centered, team-based approach. In this issue of the Archives, 3 articles investigate the impact of allied health providers' services on patient care.2- 4 This research is part of a growing literature examining the quality, safety, and cost outcomes of interventions performed by health providers without doctor of medicine (MD) degrees within team-based models of care.