This chapter will introduce the building blocks of this book’s endeavour to lay the foundations of a European Transnational Private Law. After an effort of contextualising the research project in its wider institutional and research context, we explain the central concepts, ‘European’, ‘private law’ and ‘transnational law’, that the book relies on. This is followed by an overview of the different ways in which one can, and this book does, portray the relation between the European and the transnational law in relation to private law. This chapter thus provides the conceptual and theoretical background for the book.