Published online by Cambridge University Press: 23 January 2002
Two common and seemingly independent error patterns, namely CONSONANT HARMONY and GLIDING, are examined for their typological characteristics based on cross-sectional and longitudinal evidence from young children's developing phonologies. Data are drawn from the published literature and from the developmental phonology archives at Indiana University. An asymmetry is observed such that the occurrence of harmony is found to imply the occurrence of gliding, but not vice versa. While this finding would be unexpected within contemporary derivational theories, it can be shown to follow within optimality theory from a fixed universal ranking relationship among certain constraints. Optimality theory is also argued to offer a viable developmental account with clinical implications that can serve as a further test of the theory.