PROJECT SUMMARY Syphilis rates in the U.S. have been increasing steadily since 2001, with more than 130,000 new cases reported in 2019. Left untreated, syphilis can lead to neurologic, psychiatric, cardiovascular, and other severe medical consequences, in addition to stillbirth or devastating congenital defects in infants of infected mothers. Syphilis disproportionately affects minority populations, in particular Black and Hispanic communities. Rates of congenital syphilis are also rising rapidly, paralleling an increase in rates among young women. Detection of syphilis among women of childbearing potential will be key to eliminating congenital syphilis. Current screening strategies rely on identification of symptoms or risk factors in patients attending ambulatory care, but this may result in many missed diagnoses, as syphilis can remain asymptomatic for years, patients may not perceive themselves as at risk or report relevant risk factors, and the patients most vulnerable to syphilis may also be the least likely to attend routine outpatient care. To address this issue, I created and pilot-tested an approach for universal syphilis screening in the emergency department (ED), where many vulnerable patients preferentially seek medical care. My long-term goal is to scale up this program and create a robust model that can eventually be scaled-out to other urban EDs in Chicago and across the country, and to accomplish this I will need additional data and training in implementation science. In this career development proposal, I will evaluate and improve my screening model and prepare for expansion to additional sites using implementation science strategies, informed by the Exploration, Preparation, Implementation, Sustainment (EPIS) model, a robust determinants framework in implementation science. The Exploration phase will consist of an assessment of the readiness of key stakeholders outside our institution to adopt a similar screening model. The Preparation phase will be developed concurrently to include an evaluation of the contextual factors that have contributed to successes and failures of the existing screening program, including specifically the costs associated with such programs. The Implementation and Sustainment phases represent future directions as the model is improved and sustained over time at our hospital and ultimately implemented at other institutions as part of future R01-level studies. The knowledge developed as a result of this proposal will fill important gaps in how to implement successful, context- specific ED screening programs with effective linkage to care plans, which may serve not only to increase syphilis diagnosis and treatment, but also could be applied to screening for other diseases affecting the most vulnerable populations. This K23 award will provide advanced training in implementation science, mixed methods research, and healthcare economics that will build on my background in public health and epidemiology. I wil...