Although Switzerland is a plurilingual country, most early education and care (ECEC) institutions are monolingual. Yet, new institutions have recently established English as a second language of instruction, addressing economically advantaged families. Despite the growing body of international research on language policy and practice in multilingual ECEC, only few have addressed such "privileged" institutions, and the role children play in dealing with multiple languages. We investigate the language policies and practices in daycare centres with a bilingual language policy, and particularly the children's agency in dealing with German, English, and other languages in interactions with each other, and with teachers. We draw on the concept of children's agency and view children as actors who contribute to the construction of the social and cultural world in which they live together with adults. We ask how children use languages in daycare centres, how they contribute to the centres' language practices, and how thereby different forms of agency manifest. We draw on data from a focused ethnography conducted in three daycare centres in German-speaking Switzerland. The results show that children's multilingual agency is not only enabled and limited in ECEC settings, but also actively developed in concert with language learning by children themselves.