Prior to his recruitment to Stanford as Chief of the Division of General Internal Medicine in May, 2009, Dr. Cullen was Professor of Medicine and Public Health and Director of the Occupational and Environmental Medicine Program (OEM) at Yale University School of Medicine.  He received his B.A. from Harvard College in 1971 and his M.D. from Yale University School of Medicine in 1976.  Dr. Cullen completed his residency in Internal Medicine at Yale and trained in clinical epidemiology before joining the faculty there as assistant professor in 1980.

In 1997 Dr. Cullen forged a unique academic/private partnership with Alcoa Inc., the world's largest aluminum company.  In his role as Alcoa's  Senior Medical Officer, he has extended his research into the psychosocial causes of disease in the work force, including the study of health care services, much of it in collaboration with colleagues on the MacArthur Research Network on social gradients in health for which he was selected in 1996 .  In 2006 Dr. Cullen was awarded an NIA grant to develop a model of the population determinants of chronic disease, disability and death, followed by another in 2009 to study how employees and their families use various social and health benefit options.  Availing the Alcoa "laboratory", his major research ambition is sorting out the relative contributions of and interactions among the social, environmental, behavioral and bio-medical determinants of morbidity and mortality in adults, with special emphasis on the contributions of workplace social and physcial environment.