Dr. Costenbader's research investigates the epidemiology and pathogenesis of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). She has studied associations between cigarette smoking and RA and SLE, postmenopausal hormones and oral contraceptive use and risk of SLE, antioxidants and vitamin D intake and the risks of RA and SLE. With her research group, she also studies predictors of outcomes, including cardiovascular disease, lymphoma, nephritis and end-stage renal disease, among patients with SLE, and sociodemographic disparities in the incidence and outcomes of SLE in the U.S.. She is also currently investigating biomarkers of SLE activity and disease risk, whether high dose vitamin D or fish oil intake are effective in the prevention of autoimmune disease, and disparities in access to care and outcomes among patients with SLE. Dr. Costenbader is an active clinical research mentor for medical students, residents, graduate students in epidemiology, and rheumatology fellows and junior faculty. She has trained over 40 doctoral and post-doctoral fellows. She is PI of the BWH Lupus Registry containing data on over 2300 patients with SLE, and has established the BWH Lupus Biobank, used for studies investigating biomarkers, molecular signatures and genetics.