To describe language development, two longitudinal case studies and a model for studying the patterns of interaction between children and adults are provided. Three groups of children exhibiting developmental speech and language disorders are then presented. First, stuttering children are discussed, with attention given to theory and experimental studies, therapy with the children and their parents, illustrations of the therapeutic process, treatment results, and administration of treatment programs. Second, children with severely defective articulation are dealt with; and, third, children with multiple motor-perceptual and language disabilities are considered, with projects and cases reviewed. In addition, differential diagnosis, and children in need of compensatory language training are discussed and a comprehensive approach to communication disorders in children is detailed. (JD)