Primary school teachers' attitudes, knowledge, and practical skills are vital in facilitating pupils' multilingualism. To improve language teaching and pupils' learning, it is therefore necessary to examine these constructs. This study aims to gain more insight into the attitudes, knowledge and practical skills of primary school teachers participating in an intervention to foster multilingual education. Within the framework of Dominant Language Constellations (DLC), we highlight the way languages are used and viewed within the bilingual province of Friesland, the Netherlands. Based on 23 semi-structured interviews with in-service teachers and principals, the current study investigates patterns of self-reported DLCs that emerge among primary school teachers in Friesland, as well as to what extent a typology of attitudes, knowledge and practical skills of in-service teachers can be developed.This study shows how DLCs can be applied to the study of attitudes. Our selfreported DLCs are categorized into three levels depending on how teachers view pupils' languages as part of their curriculum: Acknowledged, Semi-Integrated, or Included. Furthermore, we create a typology of inclusive, welcoming or tolerant teachers who show positive attitudes towards multilingualism and the implementation of multilingual education, are knowledgeable regarding various benefits of multilingualism, and reflect on their active use of multilingualism.