[Excerpt] Industrial relations systems involve a complex web of rules, with political, economic, labour and social inputs interacting with institutions and practices to generate outcomes. These outcomes can be wage-setting agreements, employment relationships, as well as other intangible assets, such as trust, mutual recognition, cooperation schemes, social and industrial peace. Embedded as they are in national – and, increasingly, transnational – political, economic and social environments, industrial relations systems have undergone important changes in the last decades of the past century. The aim of this research is to monitor and analyse to what extent these changes and developments have affected both the understanding and the dynamics of these systems. Based on contributions from Eurofound’s network of European correspondents in all 28 EU Member States, the report identifies and discusses key dimensions – and underlying subdimensions – relevant to industrial relations systems in Europe in the 21st century. The report also assesses existing data sources and proposes indicators that can be used to measure these different dimensions.