Distinctive features have been part of clinical work in phonological assessment and therapy. In almost all studies the set of features used was the Chomsky and Halle system. Stevens and Keyser (1989) offer a new look at distinctive features from the dimension of perceptual saliency, and account for the markedness relationship between segments. This paper explores to what extent it is possible to account for the substitution patterns in child phonologies based on the concepts of feature hierarchy, enhancement, and perceptual saliency as proposed by Stevens and Keyser. Concentrating on the consonantal substitutions in normal and disordered child speech, an attempt is made to distinguish between normal and unusual/idiosyncratic processes. Implications for assessment are discussed.