The combination of language policies, the global testing industry, and the role of STEMsubjects in school systems have been shown to undermine the inclusion of all pupils,especially with regard to language backgrounds. This lack of inclusion shows signs ofdeveloping into a point of systematic exclusion for those students. In this article we willconsider the language policies in two national contexts, the Swedish and the Luxem-bourgish ones, and specifically examine issues of in(ex)clusion in relation to multi-lingualism in STEM teaching. This study analyzes policy documents on (1) inclusion,(2)language use, and (3) STEM teaching at school in the two national contexts, using amethodology that builds on Popkewitzís (2013; 2014) approach to politics of schooling.Our results show, first, that different policies on language and multilingualism becomevisible in policy documents for primary school teaching in Sweden and Luxembourg.Secondly, this article discusses what impacts these policies may have on matters of inclu-sion, exclusion, or abjection in STEM teaching contexts at primary schools.