The report to Congress comprises a description of the current research findings on the definition, associated characteristics, diagnosis, prognosis, prevalence, causes, and treatment of developmental language disorders. Each section both reviews current literature and notes research as well as clinical needs, as related to issues of prevention. Individual author-contributed sections are on the following topics: (1) linguistic characteristics and subtypes of language-impaired children, deviance or delay, language testing, and cognitive development (S. Curtiss); (2) language intervention research (L. Olswang, C. Mateer, and B. Bain); (3) interventions for auditory perceptual and phonological disorders (C. Sloan). Among conclusions are that intervention research has tended to address one of three broad categories of inquiry--effectiveness of procedures, effects of procedures, and language acquisition process; and that research is needed in such areas as normal and disordered development of auditory and language functions and long term followup of language impaired children. Assumptions pertaining to treatment are identified and include the value of early rather than later intervention and the stimulating effect of language intervention on overall language development. The lack of adequate longitudinal studies to determine the long-term prognosis of children with language impairments is noted. A bibliography of approximately 360 items is included. (DB)