This book argues that Europeanization and globalization have led to ever-more intensive legalization at transnational level. What accounts for compliance beyond the nation-state? The authors tackle this question by comparing compliance with regulations that have been formulated in a very similar way at different levels of governance. They test compliance with rules at the national level, at the regional level (EU), and at a global level (WTO), finding that in fact the EU has higher levels of compliance than both international and national rules. The authors argue that this is because the EU has a higher level of legalization, combined with effective monitoring mechanisms and sanctions. In this respect it seems that the European Union has indeed achieved a high level of legalization and compliance, though the authors add that this achievement does not settle the related queries with the legitimacy of transnational governance and law.