Seventy-seven 4-, 5-, and 6-year-old children were presented with well-formed and ill-formed versions of 10 different sentence types. They were asked to judge the grammaticality of the sentences and correct the ill-formed ones. The sentences were presented in an interview format, developed by McDaniel and Cairns (1990, 1996). Both grammaticality judgment and correction ability improved with age. It is argued that the ability to make grammaticality judgments and to correct ill-formed sentences reflects the child's developing ability to access syntactic knowledge consciously and to employ that knowledge in the processing of sentences.