The conferencee discussions and papers presented in this volume reflect the opinions and research of 20 authorities in the field of communication development. These authorities offer new perspectives on nonverbal communication, speech reception and production, and the development of language and thought. To provide a better understanding of language development and disorders, the contents focus on two themes: individual differences among children and connectivity versus discontinuity in development. Chapter I explores social interaction between infant and mother and the manner in which infants regulate these exchanges. Chapter II describes the development of mechanisms of speech by reviewing speech perception and production, the nervous system and motor control, listening skills, and comprehension. The final chapter, on language and thought, offers differing viewpoints on children's thinking processes, provides tables detailing sequential development, and discusses language development in handicapped children. A discussion of results and implications concludes each chapter. (BJD)