It is estimated that approximately 20% of the preschool and school age population demonstrate speech acquisition disorders that are not attributable to an organic cause (NIDCD, 1994). Factors that influence the development of these are not known, but disorders of speech perception, oral-motor control, prosody, and cognitive dysfunction all have received attention as possible etiological determinants. The conclusion from these many research and clinical investigations is that PAD is not likely to have a unitary cause or profile; however, characteristics that differentiate subtypes remain elusive. The primary goal of this research is to provide a multidimensional approach to determining PAD subtypes. A dynamic systems model is being used to drive hypotheses about the factors that influence PAD development. Within this context, the impact of speech perception capabilities, including the ability of young children to extract linguistically relevant information from a variable signal, will be explored. Variations in speech production will be examined with acoustic analysis techniques with the aim of determining how variability and consistency influence speech acquisition and its disorder. Factors to be included in this analysis reflect both spectral and temporal control of articulation. Because this project also is motivated by clinical concerns, diagnostic tools that may help differentiate subtypes of PAD will be evaluated. Treatment protocols will be assessed to determine the relative efficacy of various procedures. The interaction between etiological factors, diagnostic markers and treatment efficacy will be examined, It is expected that this multifaceted approach will prove clinically useful, and at the same time, refine our theories of speech acquisition.