Work with verbal autistic children has demonstrated phonological, syntactic, and semantic production defects which are not understandable solely in terms of a developmental lag, but also suggest aspects of atypical linguistic development. This investigation is a preliminary attempt to test not only the production, but also the perception, of phonological variables in a group of autistic children, with the aim of identifying some of the atypical features of their linguistic competence when compared with normal children and children showing ideopathic mental retardation. This study also explores the potential contribution of such an approach to present-day theories of speech production and perception. Three groups of subjects were studied: normal, mentally retarded, and autistic children. In the production test, each child was given a picture naming test, constructed to elicit examples of the 24 consonant phonemes of English in initial, final, preconsonantal, postconsonantal, and intervocalic positions. The phonological perception abilities of the subjects were analyzed in two ways: the Wepman Auditory Discrimination Test (1973) and a false-positive test. The findings show that the autistic children make as many phonological mistakes as the mentally retarded and that they are particularly deficient in the production and perception of fricatives and liquids (classes mastered late in the normal developmental sequence). This suggests that autistic children are delayed in the development of phonological competence. (Author/NCR)