"Phronesis," or practical wisdom developed through experience, is an Aristotelian concept that can shed light on the capacities of patients to make health-related decisions and engage in healthy behaviors. In this article, the authors develop a conceptual framework for understanding the role of "phronesis" in lifestyle change as well as its relationship to patient activation, which is considered to be a critical component of the Chronic Care Model and patient education in general. The authors develop the concept of "phronesis" by analyzing qualitatively the comments made by 35 participants working to manage chronic health issues in a weight-loss study. The authors iteratively coded transcribed passages of exit interviews for "phronesis" and patient activation. These passages provide experientially grounded content for evaluating the use of "phronesis" and its development among individuals engaging in lifestyle change. "Phronesis" is expressed in 31% of participant responses to questions regarding the relationship between the online lifestyle intervention, participant health, and participant readiness to engage in productive clinical encounters with health care practitioners. Of those responses, 73% express some level of patient activation. The authors conclude that "phronesis" may be an important new tool for understanding successful self-management support, with potential usefulness in the creation of tailored lifestyle interventions, the development of patient activation, and the ability of participants to enact health-related behaviors. (Contains 3 tables.)