Abstract: Processes in child first language acquisition can be a locus of contact-induced language change, yet they have received little attention in the language contact literature. This chapter outlines theories and empirical case studies of children significantly influencing change during the emergence of new languages, specifically creoles and mixed languages. It discusses the role of children in the emergence of new varieties of languages, koines, and multiethnolects. In terms of structure, one way in which multiethnolects diverge from the local standard varieties is through the reduction or simplification of grammatical categories. The chapter presents some examples of child-influenced change where there has not yet been time to see if the changes will consolidate into new ways of speaking, but it is a possibility. The chapter summarizes the types of change significantly influenced by child speakers, and how those speakers’ innovations take hold in a community.