The European political arena, particularly the European Parliament, is considered a more favourable environment than the national political spheres for women. However, nearly half a century passed before a woman was appointed president of the European Commission. Women remain underrepresented in both the European Parliament and the Council. Against this backdrop, this special issue offers a comprehensive analysis of women's political careers in the European Union addressing barriers to gender equality and examining their influence on political representation. By bringing together distinguished scholars and new insights from two previously rather separate research areas—political careers in the European Union and gender representation studies—this issue sheds new light on the challenges women face. This introduction presents a multidimensional framework addressing who, what, when and how regarding key challenges women face as political leaders in the EU, such as legislated gender quotas, gendered norms, and societal stereotypes. The articles in this special issue reveal that women in European Union politics face challenges from individual and collective actors, with party gatekeeping and institutional structures playing critical roles. Gendered stereotypes and the multilevel nature of European Union politics significantly impact women's career trajectories, highlighting the need for reforms at both the European Union and national levels.