After four years in a rural training practice associated with HMC, Dr. Zapp became the Program Director. The brutal resident work hours characteristic of that era, and the personal, family and professional distress caused by acute and chronic fatigue, became a major issue with faculty and residents and in 1980, HMC started its Night Float system which it has kept to this day. In addition, RAP groups, retreats, and a one-week break at the end of the Internship year all became part of a comprehensive and successful program.

In 1993, Dr. Zapp moved to Philadelphia to the multi-hospital Crozer-Keystone Health System where he was Chair of Family Medicine and Residency Director. During his seven years at Crozer, the residency was re-designed to produce a family physician with major emphasis on ambulatory competency. A Primary Care Medical Informatics Institute was created with H.C. “Moon” Mullins, MD from the University of South Alabama, and the essential need for electronic health records in managing clinical information and just-in-time knowledge at the point of care became a major initiative. Further efforts in the American Medical Informatics Association led to the creation of the National Alliance for Primary Care Informatics with Dr. Zapp as its founding Chair. He has been a national and international speaker on medical informatics in primary care.

In 2000, Dr. Zapp moved to Mercy Medical Center in Redding, California where he served his final 3 years as a program director and participated in the Northern Sierra Rural Health Network as its Director of Medical Education.

Dr. Zapp joined the ACGME Accreditation Field Staff in September, 2003 and has since conducted over 230 site visits.

In 2007, he and his wife Iris moved from California to Topsham, Maine to be closer to family and live in the state where he began his career in medicine scrubbing hospital floors in 1959 and spent many summers vacationing with his family.