This paper will introduce the subject of language policies and practices in early childhood education across European migration societies and formulate theoretical and methodological questions. It links perspectives from applied linguistics, most explicitly sociolinguistics, and educational research on language (education) policies and practices, thus contributing to the growing body of research on language in early childhood education. Building on this broad literature review as well as on recent socio-political developments, this introduction will identify key avenues for research in this field, and argue for three essential principles: the need of a nuanced understanding of the complex interplay between language policies and language practices within early childhood education; the adoption of a perspective that considers interrelations and interactions between all actors involved (i.e. children, teachers/educators, parents, policymakers, etc.); and the commitment to a critical perspective that asks questions of power, social difference and inequality. Finally, the introduction will present the contributions to the special issue and point out how they approach the identified avenues and principles for research on language policies and practices in early childhood education.