Although migration is not a new phenomenon, European societies became more diverse over the last 20 years (Van Avermaet, 2009). This increasing superdiversity (Vertovec, 2006) interacts with intensified social, economic and political processes of unification in Europe. These dynamics have led to a renewed debate about languages and multilingualism, with a strong emphasis on education. On the one hand, multilingualism is celebrated as an asset for pupils, while on the other, it is perceived as an obstacle in processes of integration. Dominated by monolingual ideologies most European countries have reinforced monolingual education policies that are strongly practiced and echoed in local school policies. It has thus become a deeply rooted belief that submersion in the dominant language in schools is the fastest route to pupils’ school success and integration. In the lower grades of four primary schools in Ghent a longitudinal multi method study was conducted into the use of children’s repertoires as a tool for learning in mainstream classrooms. In this paper we report on the cognitive and non cognitive effects of these interventions of ‘functional multilingual learning’ on teachers and pupils. We will discuss the processes of change that have been observed in the classrooms during the intervention.