This article introduces the EUROBORD dataset. Starting from a Rokkanian conceptualization of polity formation as boundary formation, we propose a novel measurement of European integration as a combination of boundary closure and boundary control. We measure integration annually across 48 functional boundaries based on a coding of European Union (EU) law. By comparing our measure with existing measures of European integration, we provide support for its convergent validity and demonstrate its value added. We further present descriptive analyses of the historical development of the EU boundary and polity formation and propose a unified measure of European integration combining boundary control and boundary closure. The EUROBORD dataset offers the most comprehensive and fine-grained measure of European institutional integration to date.

The European Union’s (EU) Cohesion Policy is one of the main instruments to tackle the economic struggle of left-behind regions, however, only little is known about the awareness and the opinion of citizens towards this regional policy. This article examines how awareness of EU regional policies and spending preferences varies across occupations. We argue that differences in awareness across occupations are attributable to skill and responsibility differences and divergent work logics. Our analysis of a harmonized Eurobarometer dataset ( N = 82,365) provides evidence for differences in EU funding awareness and spending preferences across occupational groups, which correspond to their own material interests. In addition, citizens indicate preferences for funding decisions to be made at the most local level.

The theory of economic voting has been successfully applied to elections on different electoral levels. Less attention has been paid to the association between economic evaluations and the vote choice in European elections. In this study, we argue that economic perceptions can matter in European elections beyond rewarding or punishing the national incumbent. Instead of punishing incumbent parties, we examine electoral abstention and voting for Eurosceptic parties as a way of expressing dissatisfaction. Furthermore, we combine assessments of the national economy and the attribution of responsibility for these conditions to the European level. The findings show that voters are more likely to either abstain or to support Eurosceptic parties when they are more negative about the economic conditions in their country, but only if they attribute responsibility for these conditions to the European Union.

The Popu-List is an essential tool for identifying populist parties, but it does not provide a comprehensive analysis of their ideological varieties. This article introduces the PopulisTree, a taxonomy that systematically classifies populist actors into five main types—populist right, left, agrarian, regionalist, and valence—as well as more specific sub-types, including the populist radical right. The taxonomy's utility is demonstrated through its application to the 2024 European Parliament (EP) elections and the development of the PopulisTreeEU dataset, which provides information on the ideology, votes, seats, and EP political groups of populist parties in EP elections since 1979. Furthermore, in its dedicated website, the PopulisTree taxonomy is applied to all the parties included in the Popu-List, enabling its adoption for the study of national elections.

What factors drive trade-harmful protectionist policy interventions enacted by European Union (EU) member states? Although EU trade policy is placed under supranational competence, we highlight that trade policy decisions differ within and across the EU national governments. We explain this variation by building on the New New Trade Theory and argue that sectors dominated by highly productive ‘superstar exporters’ are less likely to receive protectionist support, yet governments with greater fiscal capacity are more likely to support these same sectors through non-tariff instruments such as subsidies – and, occasionally, even tariffs. Using data from the Global Trade Alert (2012–2022) and relying on Poisson regression analyses, we find support of our argument. These findings contribute to the literature on EU trade policy, New New Trade Theory and the domestic foundations of trade policy under supranational governance by highlighting the interaction between sectoral competitiveness and fiscal capacity.

This chapter focuses on the European Parliament (EP), an institution that has been transformed from being relatively powerless into being able to have a genuine say in the legislative process. The Parliament can also hold the European Union’s executive bodies (the Commission and Council, introduced in Chapters 9 and 10) to account in a range of policy areas. However, increases in the Parliament’s formal powers have not been matched by an increase in popular legitimacy: turnout in European elections fell in successive elections up to 2014, and while it increased again in 2019 and 2024, a growing share of the vote now goes to populist Eurosceptic parties. Thus, while the EP’s legislative power is comparable to that enjoyed by many national parliaments, it has struggled to connect with the wider European public and now has to find ways to accommodate populist Eurosceptic MEPs. Moreover, while the EP has long been committed to gender and racial equality, its MEPs and wider staff are not representative of wider society. The Parliament has also struggled to address issues of gender and race-based discrimination. The chapter explores these issues in detail. In the first section, the EP’s evolution from talking shop to co-legislator is reviewed; with its powers and influence explained in the next section; the EP’s internal structure and organization are then outlined with a focus upon the role and behaviour of the political groups; and finally, the European Parliament’s representative function as the EU’s only directly elected institution is discussed.

EU cooperation in foreign, security, and defence policy has developed rapidly since the launch of the Common Foreign and Security Policy (CFSP) in the early 1990s. Section 18.1 charts the first steps towards a common policy in this area, including the development of the Common Security and Defence Policy (CSDP) and the gradual militarization of the EU. Section 18.2 then reviews the key theoretical debates on the EU’s role as a foreign and security actor. Sections 18.3 and 18.4 analyse the main actors involved in the CFSP, focusing in particular on the role of the member states and EU institutions in the development of the policy. Section 18.5 evaluates the range of military and civilian CSDP operations and missions that the EU has undertaken to date, before examining the key challenges that the EU faces in this area in Section 18.6.

This chapter is concerned with two ‘turns’ in recent theoretical work on European integration and the EU: the rise of constructivist work and the emergence of critical theory approaches to the EU. Constructivist work is concerned with the ways in which collectively held ideas and understandings inform actor behaviour and shape political and policy outcomes. It has been applied widely in EU studies and is now firmly part of the mainstream. Critical theoretical scholarship works outside of and against the mainstream and typically seeks to advance alternative ways to think about and conduct European integration and EU governance. The chapter explores three exemplars of critical approaches to the EU: Marxism, feminism, and post-colonialism.

This chapter charts the evolution of the Single Market project from its original conception in the 1950s in the Treaty of Rome, through to more recent efforts to expand and enforce Single Market commitments in a climate of unfair trade practices and rising economic nationalism. The chapter highlights the tensions and trade-offs between the legal and regulatory strategies used to integrate markets; the challenges of creating a social market due to internal asymmetries between market integration and social protection; the efforts to facilitate the free movement of goods, capital, services, and labour; and moves to deepen the Single Market in new areas. The chapter stresses the importance of the Single Market for external relations, through the diffusion and impact of regulations beyond its borders, the strategic response to growing economic tensions, and the post-colonial impact of market practices.

This article inquires into the role of supranational redistributive policies in shaping citizens’ support for European integration. The research proposes a multidimensional concept of supranational redistribution, encompassing policies that directly target European citizens, such as unemployment and non-contributory benefit schemes at the EU level, as well as policies that target member states such as the Next Generation EU programme. Building upon the literature on policy feedback effects and historical institutionalism, the analysis proposes a theoretical model that encompasses both the direct and mediated effects of supranational redistribution. This analysis is supported by a survey experiment conducted in Spain and Italy, the largest recipients of Next Generation EU funds, yet characterised by distinct levels of public opinion and party Euroscepticism. The results show that a European unemployment benefit has the strongest potential to increase support for integration in individuals who are most likely to turn against the EU: citizens with low socio-economic resources and exclusive political identities.