Establishing Transdisciplinary Professionalism for Improving Health Outcomes is a summary of a workshop convened by the Institute of Medicine Global Forum on Innovation in Health Professional Education to explore the possibility of whether different professions can come together and whether a dialogue with society on professionalism is possible. Most of the 59 members making up the Global Forum were present at the workshop and engaged with outside participants in active dialogue around issues related to professionalism and how the different professions might work effectively together and with society in creating a social contract. The structure of the workshop involved large plenary discussions, facilitated table conversations, and small-group breakout sessions. In this way, the members - representing multiple sectors, countries, health professions, and educational associations - had numerous opportunities to share their own perspectives on transdisciplinary professionalism as well as hear the opinions of subject matter experts and the general public. Efforts to improve patient care and population health are traditional tenets of all the health professions, as is a focus on professionalism. But in a time of rapidly changing environments and evolving technologies, health professionals and those who train them are being challenged to work beyond their traditional comfort zones, often in teams. A new professionalism might be a mechanism for achieving improved health outcomes by applying a transdisciplinary professionalism throughout health care and wellness that emphasizes crossdisciplinary responsibilities and accountability. Establishing Transdisciplinary Professionalism for Improving Health Outcomes discusses how shared understanding can be integrated into education and practice, ethical implications of and barriers to transdisciplinary professionalism, and the impact of an evolving professional context on patients, students, and others working within the health care system.