The years 1650 to 1750 – sandwiched between an age of 'wars of religion' and an age of 'revolutionary wars' – have often been characterized as a 'de-ideologized' period. However, the essays in this collection contend that this is a mistaken assumption. For whilst international relations during this time may lack the obvious polarization between Catholic and Protestant visible in the proceeding hundred years, or the highly charged contest between monarchies and republics of the late eighteenth century, it is forcibly argued that ideology had a fundamental part to play in this crucial transformative stage of European history. Many early modernists have paid little attention to international relations theory, often taking a 'Realist' approach that emphasizes the anarchism, materialism and power-political nature of international relations. In contrast, this volume provides alternative perspectives, viewing international relations as socially constructed and influenced by ideas, ideology and identities. Building on such theoretical developments, allows international relations after 1648 to be fundamentally reconsidered, by putting political and economic ideology firmly back into the picture. By engaging with, and building upon, recent theoretical developments, this collection treads new terrain. Not only does it integrate cultural history with high politics and foreign policy, it also engages directly with themes discussed by political scientists and international relations theorists. As such it offers a fresh, and genuinely interdisciplinary approach to this complex and fundamental period in Europe's development.