Kristen Underhill is an authority on health law and policy, with expertise in medical malpractice, the structure of the insurance system, fraud, and abuse. Her research focuses on how the law influences individual decisions about risk and health behavior by arranging incentives, shaping opportunities, influencing preferences, and communicating information about social norms. She is currently at work on a five-year, National Institutes of Health study of access to new HIV prevention technologies. Her work has been cited by media including the BBC and The Boston Globe.

Underhill holds a D.Phil. in evidence-based social intervention from the University of Oxford. She teaches a variety of courses, including one focused on the uses and limits of tort law for advancing public health.