Chapter 22 in The Handbook of Psycholinguistics, edited by Eva M. Fernández & Helen Smith Cairns. Chapter summary: This chapter describes the language production system and samples research on its development in children. The field of language acquisition uses children\u27s speech to buttress claims about their linguistic competence. Such reasoning assumes two forms: (a) lack of a structure in children\u27s speech indicates that it is not part of their competence, and (b) the frequent occurrence of a non‐adult structure indicates a non‐adult grammar. We argue that it is essential to determine how a production system might separately influence child speech. Performance models can provide alternative accounts for some of the phenomena attribu...