While still in his influenza fellowship at the Baylor College of Medicine in Houston, Texas, Dr. Dacso joined the faculty there in 1978 as an Instructor of Internal Medicine. He received dual appointments there two years later as a Clinical Assistant Professor in the Department of Medicine, and as an Assistant Professor in the Department of Microbiology and Immunology. Dr. Dacso later moved to the University of South Alabama where he rose through the academic ranks and eventually became the Chief of both the General Internal Medicine Division and the Infectious Diseases Division, as well as the Vice Chairman of the Department of Medicine.

In 1988, Dr. Dacso joined the University of California at San Diego where he served as the Chief of General Medicine and Geriatrics at the VA Medical Center, the Chief Medical Officer for the VA Outpatient Clinic, the Director of the UCSD Internal Medicine Group, and held the appointment of Professor of Medicine.

Dr. Dacso rejoined Baylor in 1992 as the Vice Chair for Clinical Affairs in the Department of Medicine, and the Chief of both General Internal Medicine and International Medicine. He became the Vice Chairman for Strategic Development there in 2000, and assumed his current positions at Houston Methodist and the University of Houston in 2005.

Dr. Dacso's research focuses on the development of novel delivery systems for healthcare in communities, especially medically underserved areas in the U.S. and the developing world. His basic research investigates the cultural and theoretical bases of health care decision making. His applied research program develops non-invasive devices for remote chronic disease monitoring and prediction. Dr. Dacso has developed a device that enables patients with congestive heart failure to accurately track their cardiac output at home. He has developed similar devices to measure blood glucose levels for diabetes, promote self-management in pediatric asthma, promote healthy aging in place, and evaluate exercise thresholds in real-time.