The general objective of the present research is to provide data on the temporal and spectral components of children's normal and functional misarticulation of the /s/ sound. Two related objectives in this investigation are 1) to measure those acoustic components of misarticulated /s/ at fixed intervals over a substantial period of time, and thus describe more precisely the changes that might occur during 'normal' mastery of a speech sound, and 2) to measure those acoustic components of misarticulated /s/ as a function of clinical intervention, that is, training a child to 'shape' a correct /s/ sound. The experiments use as subjects children aged 4.0-6.0 years; one group of children has 'normal' /s/ articulation, whereas children in the other group have consistent misarticulation of the the /s/ sound. A speech sample of mono- and bisyllabic items, in which the /s/ sound is varied according to position-in-word and phonetic context, provides the basic material for acoustic analysis. Children produce multiple samples of each item, and recordings of all speech samples are made under laboratory conditions. Spectrographic, oscillographic, and wave-analyzer techniques are used to derive the temporal and spectral data.