Mary Charlson, M.D., is the William T. Foley Distinguished Professor of Medicine and chief of the Division of Clinical Epidemiology and Evaluative Sciences Research at Weill Cornell Medical College. As a clinical epidemiologist, her work has focused on developing interventions targeted at improving outcomes in chronic illness. She developed the widely used Charlson Comorbidity Index. She has a long track record of successful randomized controlled trials (RTCs) among patients with chronic illness and has been the principal investigator on eight National Heart, Lung, and Blood Institute-funded RCTs involving 2,725 patients. She is co-principal investigator on a PCORI-funded RCT to reduce unplanned hospitalizations in patients with high comorbidity.