This monograph describes the National Speech and Hearing Survey (NSHS) database and examines the prevalence of articulation deviations, voice deviations, stuttering, dialects, hearing impairments, and multiple deviations. Literature on the coexistence of communication disorders is then reviewed, focusing on coexistence in articulation and language disorders, in voice disorders, in stuttering and disfluency, and in hearing disorders. Studies at West Virginia University using the NSHS database are reviewed. Research needs and future NSHS applications are outlined. The monograph concludes that speech, language, and hearing disorders frequently coexist, and calls for examination of communication systems as interrelated systems and for treatment plans that attend to the various disorders in the most beneficial way. Appendices list NSHS test sites, stimulus materials used in speech testing, sample NSHS data sheet, and subject data. (Contains approximately 260 references.) (JDD)