A social epidemiologist by training, Decker focuses her research on gender violence—sexual assault, intimate partner violence, and sex trafficking—and its implications for HIV and other aspects of sexual and reproductive health, especially in marginalized populations, including urban women, adolescents, and those involved in transactional sex or sex work. She is currently developing clinic-based interventions to mitigate the health consequences of violence, as well as primary mixed-methods research strategies to understand the mechanisms by which violence influences sexual health and HIV risk.