Over the years, Eurosceptic parties have grown in both number and electoral support, together with the politicisation of European Union (EU) integration cleavage within European national polities. The term Euroscepticism denotes different aspects and degrees of opposition to the EU. For example, criticisms can point to institutions, policies, procedures, actors, as well as the integration project per se. Moreover, Euroscepticism can refer to either voters or elites. In this article, we focus on national political parties. We propose a narrow conceptualisation of Euroscepticism, by linking this concept to the concept of anti-system party. Based on several indicators, we measure the success of Euroscepticism in the member states. In our analysis, we ask why anti-system parties emerge and gain votes in some European countries, and not in others. The empirical part of the article presents a preliminary configurational analysis of necessary and sufficient conditions of Euroscepticism and related electoral successes.