This chapter introduces the scientific focus of the book, around three main issues. First, it distinguishes sustainability and transition while pointing out the filiations and uses of both repertoires by different actors. Second, this positioning also stands out in relation to the literature on renewable energy issues. Three main findings are underlined: (i) a large part of the social science body of literature takes a “global” view of the energy transition; (ii) many of the published works on energy transition in Europe favour one level of reflection or action over others: the scale of the European Union is frequently chosen, but it can also be the scale of a country or of local community projects; (iii) it is rare to combine a diversity of social sciences to capture both renewable energy transition frameworks and practices. Third, the chapter introduces the multidisciplinary and relational approach which is applied to the Upper Rhine Region case study to address both a multilevel and stakeholder perspective in a concrete way through material and intercultural border issues. As this book develops three main perspectives – law, economics and sociology – the contribution of each part to the main arguments of the work is presented briefly.