The aim of this study was to examine what four-year-old children repair in their speech. For this purpose, conversational self-repairs (N = 316) made by two typically developing Finnish-speaking children (aged 4 ; 8 and 4 ; 11) were examined. The data comprised eight hours of natural interactions videotaped at the children's homes. The tapes were analyzed using conversation analysis. The children made phonological, morphological, syntactic, lexical and non-linguistic self-repairs, and also inserted additional material into their utterances. Finnish-speaking children made more syntactic and fewer morphological self-repairs than the previous research on English-speaking children suggests. Furthermore, most self-repairs were found in talk during pretend play. In designing and engaging in such play, the children skilfully used self-repair to match their talk to meet the requirements of different interactive activities and co-participants. Finally, contextual analysis of children's self-repairs showed that these were also socially motivated, and not just related to slips or errors in speech.