Although much attention has been focused on individual-level drivers of burnout in primary care settings, examining the structural and cultural factors of practice environments with no burnout could identify solutions. In this cross-sectional analysis of survey data from 715 small-to-medium-size primary care practices in the United States participating in the Agency for Healthcare Research and Quality's EvidenceNOW initiative, we found that zero-burnout practices had higher levels of psychological safety and adaptive reserve, a measure of practice capacity for learning and development. Compared with high-burnout practices, zero-burnout practices also reported using more quality improvement strategies, more commonly were solo and clinician owned, and less commonly had participated in accountable care organizations or other demonstration projects. Efforts to prevent burnout in primary care may benefit from focusing on enhancing organization and practice culture, including promoting leadership development and fostering practice agency.