Public diplomacy matters to the G20. As the self declared 'premier international forum for economic cooperation', the G20 has global interests and ambitions. The G20 requires the ongoing engagement and support of global public audiences. Simply put, it is a matter of effectiveness, legitimacy and credibility. Yet as an informal, nomadic institution that brings together a diverse array of high profile actors, global, interests and issues, the G20 also presents unique opportunities and challenges to public diplomacy's agenda. The wider narrative of the G20 as an inclusive institution capable of involving publics in the process of global change is underexplored. This book asserts that public diplomacy is the key to the G20's ongoing development, and proposes a fourth phase to John Kirton's (2013), current three phased approach: the mobilization of the many. By examining the many facets of G20 public diplomacy, Byrne contributes to the evolving understanding of the G20 while offering new insights on the evolving practice of public diplomacy beyond the traditional state-centric perspective.