Based on the example of the Polish delegation to the European Parliament, the book examines the factors influencing the cohesion and stability of EP national delegations. It takes into account the impact of institutional arrangements such as the electoral law and the candidate selection process, the ideological and programmatic profiles of political parties, the career paths of MEPs, affiliation to political groups in the EP, group switching, as well as the significance of Euroscepticism and national divisions transferred to the European level. It is not a typical case study, as the...