Much of his work has focused on trauma, violence and anxiety, particularly the impact of post-traumatic stress disorder and other anxiety disorders on the families of those directly affected. He has trained numerous student and mental health professionals, published more than 80 articles and book chapters, and presented numerous papers and workshops. Previous positions include clinical research positions at the Center for the Treatment and Study of Anxiety and the National Center for PTSD, as well as academic appointments at the Medical College of Pennsylvania, Tufts University, Boston University and the University of Pennsylvania.