He is a Certified Group Psychotherapist and is listed in the National Register of Health-care providers in Psychology. He has extensive experience in several treatment methods, both brief and long term, including psychoanalysis. Dr. Hopper has been a member of the Board of Directors of the Colorado Psychological Association and a former executive board member of the American Group Psychotherapy Association (AGPA) and is an AGPA faculty member. He is a licensed psychologist in both Colorado and Missouri.