He has practiced the full scope of family medicine in a rural community of 4,000 people in Alaska for the past 21 years. Cullen works in a small group practice and is both chief of staff and director of emergency medical services at Providence Valdez Medical Center. He has been actively involved in residency and medical student teaching for more than 18 years, providing comprehensive training in rural health care. He is an associate clinical professor at Dartmouth University.