This study extends prior investigations of children's abilities to conceptualize distinctive phonological features in development. The purpose was to establish the relationship between a child's productive and conceptual knowledge, and to examine its potential influence on phonological change. Six children evidencing phonological disorders (aged 3;4 to 5;7) participated in evaluations of the productive sound system and the metalinguistic ability to classify phonological information, with particular emphasis on fricatives. Then, children were enrolled in clinical treatment aimed at accurate production of fricatives. Following treatment, production and classification abilities were again tested. Results indicated that if a child's productive knowledge of distinctive featural contrasts changed following treatment, there was also a corresponding change in conceptual knowledge. The specific featural dimensions that were used to classify phonological information were either in parallel to, or in advance of, those features also used in production by the child. Conceptual knowledge was thus equal to or better than productive knowledge for these children.