Book excerpt: This volume provides an overview of the evolution of NATO, alliances and global security governance in the twenty-first century.For so-long the cornerstone of the transatlantic partnership, the evolution of NATO has profound implications for the co-operative or competitive nature of transatlantic relations and regional and global security governance. As NATO moves into the twenty-first century its role, purpose, utility and very existence as the core transatlantic security alliance is increasingly questioned.For many observers with a more profound understanding of the evolution of NATO, such self-doubt has been a constant feature of NATO throughout its existence. But contemporary debates that question the utility of NATO and its collective security role do appear more strident, extreme and are expressed in a more determined fashion than arguments between allies on how best to secure the Cold War collective defence role. The Iraq War widened the spectrum of opinion as to NATO's future to an unprecedented degree. An interesting feature of this intense debate is that only the extremes tend to prick public consciousness - NATO as train-wreck or NATO in robust and rude health.Understanding NATO in the 21st Centurywill appeal to students of NATO, international security and international relations in general.