This century has been labelled the age of migration. Even in a globalized world, Luxembourg takes an exceptional position with its demographic profile – not only the high percentage of foreign nationals but also the heterogeneity of this group: Recent arrivals live alongside those who arrived one, two or several generations ago. One consequence of this multinational mix is an increasing number of multinational families and children growing up in multinational households. In their daily lives people of different nationalities and language backgrounds meet. Minorities and majorities constantly shift and people may develop different acculturation strategies depending on context. Previous research within Luxembourg has shown that a multicultural environment actually heightens awareness of nationalities. What are the consequences for identity construal in such a complex environment, requiring constant switching between different cultural frames? Focussing on adolescence, a formative time for reflection and identity development, identity construal among adolescents will be assessed, using a multi-method approach, including experience sampling, quantitative measures and interviews. The key question is if, how, when and why nationality becomes a salient part of identity construal and how this relates to outcomes such as wellbeing and academic achievement. The role of parental cultural value transmission and the educational context will also be explored. Teachers will be included by means of questionnaires and focus groups. The goal is to assess how diversity within classrooms is used and to compare outcomes in terms of academic achievement and subjective wellbeing of students. What are the techniques to maximize the benefits resulting from diversity and to minimize potential detrimental effects? By identifying best practices for education and learning the project aims to make a contribution to social and economic cohesion. Luxembourg is an ideal place to study these phenomena and generalizations can then be made to other contexts and countries.