One of the core concerns of the research undertaken by GREIP has been to develop an interdisciplinary approach to plurilingualism that could be useful in education. This approach was established by taking into consideration, the competences that make it possible to acquire the knowledge, orientations and practices that allow effective participation in a variety of everyday interactions in educational and social contexts (Codó, Nussbaum, & Unamuno, 2007; Nussbaum & Unamuno, 2006). Giving an account of how plurilingualism and, more specifically, plurilingual competences should be managed in the classroom has become a research subject strongly connected with the need to understand complex teaching-learning situations. This chapter concentrates primarily on the methodological aspects of the project. The goal of this chapter is to explore the network of collaboration that was built up throughout the life of the project, mobilizing the various agents who took part in it. The authors believe that it is those relationships that allowed them to progress in identifying and describing the ways that young people categorize school and non-school linguistic practices and give meaning to the socio linguistic context that frames their language socialization. Resources for recommended reading, and websites with resources mentioned are also provided. [A Spanish version of this chapter is also included in the book. For the complete volume, "Qualitative Approaches to Research on Plurilingual Education," see ED573580.]