We review accumulating evidence that implicates the language encoding and production system in children and adults who stutter. Stuttering is unique in its onset during the most dynamic stages of language acquisition, after apparently successful mastery of early language skills. We review older theories of stuttering that have given way to an understanding of stuttering's underlying bases in cortical and subcortical networks. Behavioral data suggest strong influences of language encoding demand on the frequency and location of stuttered events; psycholinguistic findings suggest atypical language processing in the absence of overt speech. We discuss the probable neuroanatomical and neurophysiological bases of these findings, with implications for therapeutic intervention. Expected final online publication date for the Annual Review of Linguistics, Volume 10 is January 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.