Few studies have focused on the importance of peers for child language development in the preschool years. The aim of this study was to assess whether peer expressive language skills predict language ability of preschool-aged children attending Norwegian Early Childhood Education and Care (ECEC) centers. Data from the Behavior Outlook Norwegian Developmental Study (BONDS) were used, including 539 children in 57 centers. Peer expressive language at age two was not, on average, associated with child's language ability at age four. However, belonging to a peer group with better language skills seemed to attenuate language differences due to educational background. Implications for researchers and policy makers are discussed, namely with regards to the importance of mixed ability classes and instruction strategies aimed at raising the overall competence in the peer group and not only of the less skilled students. (author abstract)