Many children in Sweden today are multilingual and one of the public libraries' missions is to support children in their language development. This essay examines how public libraries work towards the target group of multilingual children by interviewing five librarians at five different libraries. The empirical evidence of this essay shows that libraries rely on research when they work with multilingual story times, singing times and other programs to support children's language development. Libraries face difficulties in their work, partly because it is difficult to reach the target group. It is also a challenge to find books in different languages, for example. In order to overcome the difficulties, the libraries collaborate with various actors, such as preschools, child care centers and home language teachers. Collaboration can also be a challenge. The essay is based on the collaboration theory to investigate how different aspects can promote or inhibit collaboration.