This book is divided into three parts. The first provides the theoretical background, and concepts such as Identity, Nation, Ideology, Discourse or Language are defined and discussed. Part two describes the processes of data collection and data analysis followed in the project. The data were collected following an ethnographic approach, in two European cities: Vitoria- Gasteiz (Euskadi) and Lleida (Catalonia). Membership Categorization Analysis is used on the data, although it is important to mention that the analytical framework is that of Critical Discourse Analysis, in which the analyst adopts a critical stance towards the social problem under scrutiny. The results are presented in part 3. The analyses show how people negotiate our national allegiances and language ideologies in interaction, and how social discourses are reproduced or challenged through our participation in these events.