Full edition for scientific use. The RECONNECT Survey on EU Reform Preferences dataset contains responses from 12.000 eligible voters in six EU member states (Denmark, Germany, France, Hungary, Poland, Spain), with 2000 respondents per country. Respondents participated in two survey experiments: A conjoint experiment on EU decision-making and a vignette experiment on violations of EU rules and blame attribution. In addition to a number of questions on socio-demographics, the dataset also contains items measuring a wide range of political attitudes, including attitudes toward the EU and European integration, populism and societal marginalization, identity, cosmopolitanism and threat perceptions, political satisfaction and trust, party preferences, policy preferences, political interest, and political knowledge.