Great power competition is back on the world stage, and todays international system is home to regional influences on great power relations that cannot be ignored. The United States unipolar moment is long over, and Chinas hegemonic ambitions find expression in a comprehensive global competition with the US that plays out across multiple spheres of world politics. The US-China rivalry can be felt in geostrategic, economic, governance, diplomacy, intelligence, and technological spheres, to name a few. Most accounts of China-US relations in the context of great power conflict emphasize the many ways in which this rivalry has a ripple effect across the globe, with an impact upon the relations and interests of smaller powers. And while these effects are considerable and important, this book contends that attention must also be paid to the ways in which smaller, regional states have the potential to shape this great power rivalry. Put simply, great powers both shape, and are shaped by, smaller states. Any understanding of contemporary great power relations between the US and China requires both a top down, but also a bottom up consideration of the interplay between great powers and regional ones. Often the interests of regional powers are rooted in domestic considerations such as their identities and national interests, and these influences transcend borders and often have an impact upon the great powers. This book considers these smaller, regional actors and attempts to measure the extent to which they influence the US-China rivalry. For this study, constructivist theory, which prioritizes the agency that regional powers enjoy, is loosely used as a tool to enable a more robust and comprehensive understanding of the influences on the contemporary great power relationship. Each of the books chapters represents a region, or part of a region, that enjoys a considerable impact upon US-China relations.