This Career Development Award (K01) is a proposal to further my education and training in advanced biostatistics, econometrics, and health outcomes research through didactic courses and contact with a primary mentor and multidisciplinary group of experts in diverse fields ranging from infectious diseases to economics and health behavior research. The goal of this advanced training is to acquire the knowledge and skills necessary to comprehensively study the epidemiology and outcomes of surgical site infections (SSI) after breast cancer surgery, that may impact as many as 18,000 women each year in the United States. A prospective longitudinal cohort design will be used to determine accurate incidences and risk factors for SSI within 1 year after breast-conserving surgery, mastectomy, and mastectomy with immediate reconstruction. Clinical outcomes of SSI, including consequent further surgical interventions, antibiotic administration, and development of antibiotic resistance will be measured utilizing inpatient and outpatient follow-up data. The impact of SSI on overall health-related quality of life, depressive symptoms, sexual functioning, and specific issues related to the healing breast incision will be assessed multiple times after surgery. From the societal perspective, the economic costs attributable to SSI following the different types of breast surgery will be quantified using financial data obtained from inpatient hospitalizations and outpatient clinic visits. The advanced training received in biostatistics will allow for the creation of detailed statistical models to calculate the attributable costs of SSI in both the inpatient and outpatient setting. Determining accurate incidences and identification of specific risk factors for development of SSI in this surgical population will facilitate the development of risk stratification indices and infection control interventions to prevent these infections following breast cancer surgery.