His research explores the utilization of health services, with an emphasis on mental health care. His main focus has been to identify patient, provider, and system characteristics that are associated with low treatment rates for specified mental health and general medical conditions. Through his research, Dr. Harman has become an expert on analysis of large secondary datasets, such as medical claims data, large national health surveys, and other administrative data. He has particular expertise in methodological techniques for analyzing large observational datasets. Specific elements of his research agenda involves documenting and understanding barriers to mental health services as well as the impact of health insurance on utilization of and expenditures for health services.