This chapter sets out our approach to the book in the context of theoretical debates and methodologies applied in feminist (legal) research. We unravel the immensely multi-layered concept of ‘gender’ in the context of the existing literature exploring European integration theories and elucidate what we understand the terms ‘gendered perspective’ and ‘gender lens’ to entail in the context of our research. We also explore the role of the Court of Justice of the European Union as a political and legal institution and try to illuminate our chosen methodology.