Dr. McMahon earned his medical degree from the University of Vermont in Burlington and completed his internal medicine residency at Strong Memorial Hospital at the University of Rochester. He completed two postdoctoral fellowships in gastroenterology and health systems management at Yale University, where he also received his master's in public health. He is board certified in both internal medicine and gastroenterology. His clinical interests include gastrointestinal diseases, disease prevention, and health maintenance. His research interests include medical care quality, organization, and financing.