This paper investigates multilingualism as a new paradigm established within EU language policy. It is argued that if multilingualism is not to be merely a scientific research area and a topic of language policy discussions, but is to become reality in modern language teaching, then initial teacher education and continuing professional development for language teachers is addressed as well. While language policy developments have been signaling a pressure for reform for years, and research on learning multiple languages has yielded results which are relevant for language teaching, a paradigm shift in teaching practice is still facing a number of obstacles. Formulating guidelines for improved teacher education and development derived from the European discourse and criticizing the ‘circuit of monolingualism’, the article eventually arrives at three principles to be observed if teachers are to be qualified as experts for multilingualism as well: taking up multilingualism as a topic, making general didactic developments like differentiation and learner autonomy exploitable for multilingualism, and enabling positive learning experiences across languages during the language teacher education. All three principles call for breaking with the monolingual habitus of education.