Cohesion policy is one of the longest-standing features of the European construction; its roots have been traced as far back as the Treaty of Rome. Over time, it has become one of the most politically salient and sizable policies of the European Union, absorbing approximately one-third of the EU budget. Given its principles and “shared management” approach, it mobilizes many different actors at multiple territorial scales, and by promoting “territorial cooperation” it has encouraged public authorities to work together, thus overcoming national borders. Furthermore, cohesion policy is commonly considered the most significant expression of solidarity between member states and the most tangible way in which EU citizens “experience” the European Union. While retaining its overarching mission of supporting lagging regions and encouraging the harmonious development of the Union, cohesion policy has steadily evolved and adapted in response to new internal and external challenges, such as those generated by subsequent rounds of enlargement, globalization, and shifting political preferences regarding what the EU should be about. Just as the policy has evolved over time in terms of its shape and priorities, so have the theoretical understandings of economic development that underpin its logic, the nature of intergovernmental relations, and the geographical and administrative space(s) within which the EU polity operates. For example, whereas overcoming the physical barriers to economic development were the initial targets in the 1960s and 1970s, and redesigning manufacturing clusters were those of the 1980s and 1990s, fostering advanced knowledge and technological progress became the focus of cohesion policy in the new century. At the same time, cohesion policy also inspired or even became a testing ground for new theories, such as multilevel governance, Europeanization, or smart specialization. Given its redistributive nature, debates have proliferated around its impact, added value, and administrative cost, as well as the institutional characteristics that it requires to function. These deliberations have, in turn, informed the policy in its periodic transformations. Political factors have also played a key role in shaping the evolution of the policy. Each reform has been closely linked to the debates on the European budget, where the net positions of member states have tended to dominate the agenda. An outcome of this process has been the progressive alignment with wider strategic goals beyond cohesion and convergence and the strengthening of linkages with the European Semester. However, some argue that policymakers have failed to properly consider the perverse effects of austerity on regional disparities. These unresolved tensions are particularly significant in a context denoted by a rise of populist and nativist movements, increasing social discontent, and strengthening Euroskepticism. As highlighted by research on its communication, cohesion policy may well be the answer for winning back the hearts and minds of European citizens. Whether and how this may be achieved will likely be the focus of research in the years ahead.