Research by Dr. Mary Ann Chiasson centers on the epidemiology of HIV, particularly risk factors for sexual transmission and biomedical and behavioral prevention; reproductive health; and maternal and early childhood obesity. Her current HIV-related research focuses on the relationship between the Internet and high risk sexual behavior among men who have sex with men and CHAIN, an ongoing prospective cohort study of representative samples of persons living with HIV/AIDS in New York City (NYC) and the Tri-County region. She co-directed the HIV/AIDS Epidemiology course at Mailman from 1989-2015. Dr. Chiasson served in various capacities at the New York City Department of Health from 1986 - 1999 including nine years as an assistant commissioner of health with scientific and administrative responsibility for AIDS Surveillance, HIV/AIDS Research, and Vital Statistics and Epidemiology. In 1999 Dr. Chiasson was appointed vice president for research and evaluation at Public Health Solutions (PHS), a large non-profit organization that provides health-related services, conducts demonstration and research programs, and offers management services in order to improve community health and strengthen health policy. She retired from PHS in 2018.