Children's self-monitoring of language production, as it is reflected in spontaneous speech repair, was studied. Recordings of the speech of three children aged two to three were analyzed for spontaneous phonological, morphological, lexical, and syntactic repairs. After tabulation, repairs were identified as "for the listener" (reflecting the child's need to make himself understood) or "for the system" (reflecting self-monitoring of those parts of the language that the child is in the process of acquiring). A similar analysis was made of the speech of several children aged four to seven, in a pretend play situation. Here it was found that monitoring and self-correction were aimed at the use of speech appropriate to the role being played. The overall conclusion of the study is that children monitor the gap between their knowledge of language from input received on the one hand, and their own language production on the other. This monitoring results in repairs which eventually close the gap. (JB)