This article is a guide for researchers interested in assessing the effectiveness of serious computer-based games (or video games, digital games, or electronic games) intended to improve health and health care. It presents a definition of health games, a rationale for their use, an overview of the current state of research, and recommendations for conducting studies with health games. It presents three approaches to conducting controlled studies of health games, including learning and behavioral outcomes research, value added research, and media comparison research. (Contains 4 tables.)