Since 2008, physician-led primary care practices have decreased as physician's encounter sustainability challenges because of government regulations and the requirements of the Affordable Care Act. The problem is that some physician-led primary care practice leaders lack strategies to sustain a medical practice longer than 5 years. The purpose of this study was to explore strategies primary-care practice leaders use to sustain a practice longer than 5 years. This study followed a case study design, including a purposeful sampling of 3 physician-led primary care practice leaders in southern Indiana. Open-ended semistructured interviews were conducted and triangulated with company policies and procedures as well as government statistics. Coded data and themes were identified using the complex adaptive systems theory. Three sustainability themes emerged: (1) patient engagement, (2) relationship development and retention, and (3) adaptation and innovation. The recommended action is for physician leaders to apply the strategies to develop their primary care medical practices. Results from the study may contribute a positive social change by presenting strategies to develop and sustain physician-led primary care practices, which could lead to an increase of primary care medical practices, resulting in more patients having access to primary care physicians.