Mr. Callahan was born and raised on a small family farm in northeastern Maryland. He holds an Associate degree from Harford Community College, a Bachelor's degree from St. Mary's College in Maryland and graduate course work at both Indiana University of Pennsylvania and Central Michigan University. He is a graduate of VA's Executive Career Field Training Program (ECF) and Healthcare Leadership Institute.

Mr. Callahan began his VA career in 1993 as an Occupational Safety & Health Manager at the Lebanon VA Medical Center. In 1997, Mr. Callahan became the Facility Manager at the Butler, PA, VAMC and in December 2000 he moved to the three division VA Pittsburgh Healthcare System (VAPHS) as the Vice President for Facility Management. In October 2003, he became the Associate Medical Center Director for Site Management at VAPHS, and was responsible for day-to-day operations of 3,000 employees serving over 57,000 veterans. Mr. Callahan's diverse experience also includes serving as an Adjutant Professor at Millersville University, a program manager within the Department of Defense, and as a researcher in the chemical industry in the late 1980s.

Nationally, Mr. Callahan served on numerous administrative taskforces and work groups. He brings with him a wealth of experience in strategic planning, tactical operations, organizational and healthcare redesign and is active in mentoring future VA leaders. Mr. Callahan is an advocate for all veterans and his mantra is "Excellence in All". He believes as civil servants we are called to a higher purpose than ourselves, values honesty, integrity creativity and loyalty and is personally committed to serving America's heroes. He is very interested in open communication, employee development and ways to reward and motivate employees.