Jack practiced internal medicine with the Williamstown Medical Associates, a multi-specialty group of physicians in Western Massachusetts for nearly thirty years, following which he enrolled in the graduate program at Antioch University New England, and received a MS degree in management in l996. A graduate of Williams College, he received a medical degree from Johns Hopkins University in 1957, and post-graduate training at the Johns Hopkins Hospital and New York Hospital-Cornell Medical Center. He was a Rockefeller Foundation Fellow in Preventive Medicine at Makerere Medical College in Kampala, Uganda, in 1963-64. He is a Fellow of the American College of Physicians. In 2015 he earned an Honorary Doctorate in Business from Antioch University.
He was a Trustee of Williamstown Savings Bank for 28 years, and Founding Chairman of MountainOne, a mutual holding company with three banks plus insurance and brokerage interests. Jack has served as a Founding Director of the Fund for Williamstown (an endowment for the town) and the SEE Fund (Sustaining Educational Excellence) at the regional public high school. He served as a Selectman in Williamstown for six years, a Director of the New Hampshire Lakes Association, and is currently a Trustee of the Lakes Region Conservation Trust.
Jack is the author of several scientific papers, and is a contributing author/editor of Bear Island Reflections, a history of an island community in New Hampshire.