Our paper presents the results of a research conducted with teachers in "bridging classes" welcoming young migrants who entered the Belgian territory for less than one year. As a result of the recent evolution of migration dynamics in Europe, they have to manage an unprecedented and increasing cultural heterogeneity of the pupil population. It is therefore essential that they acquire "intercultural skills", which are currently not enough developed in their initial training programme, to achieve the constitutional goal of school and social inclusion. During our study, we met 30 teachers working in this bridging classes in order to better understand their vision of the cultural diversity management in schools and to assess how they perceived their own level of intercultural competence and their sense of self-efficacy, in relation to their available pedagogical resources. We collected data through two questionnaires and a semi-structured interview. Our results show that these teachers are compelled to manage the pupils' diversity in a pragmatic way, believing that they are not professionally trained to do it. The experience, however, strengthens their self-efficacy but they feel less competent in the different clusters of diversity management. They, therefore, seem to base the effectiveness of their pedagogical action on their ability to respond to the diversity of pupils' needs by individual adaptation of their practices and to manage social relations within the classroom by creating a climate of respect between pupils from different backgrounds. They finally recommend diverse improvements that would enable them to promote school inclusion in the longer term, to feel more effective in their welcoming mission, and to ensure better opportunities for newcomer pupils to be empowered through education