This book seeks to help shape the debate surrounding power and polarity in the twenty-first century, both by assessing the likelihood of US decline and by analysing what each of the so-called 'rising powers' can do.As the twenty-first century moves out of its first decade, American supremacy continues to generate intense debate about the nature, quality and sustainability of US power. At the same time, significant developments in four rising powers - China, Russia, India and the European Union – have provoked analysts to ask whether multipolarity is a realistic prospect.Multipolarity in the 21st Century assesses the likelihood of a multipolar world developing, either by a marked US decline and or by the ability of these putative ‘rivals’ to continue to rise to the level necessary to be credibly considered a superpower. Written by a combination of emerging scholars and recognised experts, this volume will provide a timely and authoritative analysis of one of the most controversial and compelling security debates of the twenty-first century.