The pronunciations of children do not merely represent accidental misses with respect to adult pronunciation. Children employ substitutions and deletions in highly systematic ways; child pronunciations reflect a set of simplification strategies. The major common processes of both normal and abnormal child phonology result in simplification of either linguistic output or the underlying phonological system of the child. The processes include: (1) cluster simplification; (2) final consonant deletion; (3) assimilations of various sorts; and (4) processes of category collapse which include liquidation (liquids and glides become glides), voicing avoidance (final voiced consonants are collapsed with the unvoiced category), and stopping (initial fricatives, affricates, and stops become stops). Even some processes which apparently result in complication of the child's output (viz., when the child adds phonetic elements to adult forms) are, in fact, simplifications since they reduce the child's speech effort by maximizing the production of certain preferred syllable shapes. (Author/DD)