The introduction is structured in four sections. It first makes an assessment of the very vast scientific literature that has been devoted to the European Parliament (EP), and explains that it is structured according to two dimensions: disciplines and methods. It then examines the six main topics addressed by scholars studying the EP. In a third section, it analyses the evolutions of the research in the field, underlining its recent decline, and deals with issues such as routinisation and over-specialisation. The introduction, moreover, underlines the need for new research agendas to account for the many evolutions of the EP. It finally describes the contents of the volume, which is structured in four parts, dealing respectively with the place of the EP within the EU political system, its role in the EU policy-making, its election and internal politics, and lastly its impact on EU policies.