Physicians are being increasingly called upon to engage in leadership at all levels of modern health organizations, leading many to call for greater research and training interventions regarding physician leadership development. Yet, within these calls to action, the authors note a troubling trend toward siloed, medicine-specific approaches to leadership development, and a broad failure to learn from the evidence and insight of other relevant disciplines, such as the organizational sciences. The authors describe how this trend reflects what has been called the “Not-Invented-Here Syndrome” (NIHS)—a commonly observed reluctance to adopt and integrate insights from outside disciplines—and highlight the pitfalls of NIHS for effective physician leadership development. Failing to learn from research and interventions in the organizational sciences inhibits physician leadership development efforts, leading to redundant rediscoveries of known insights and reinventions of existing best practices. The authors call for physician leaders to embrace ideas that are “proudly developed elsewhere” and work with colleagues in outside disciplines to conduct collaborative research and develop integrated training interventions to best develop physician leaders who are prepared for the complex, dynamic challenges of modern health care.