4. This last summary is partly from chapters two, three, and four in Haslett, B. B., & Samter, W. (1997). Children communicating: the first 5 years. Mahwah, N.J.: Lawrence Erlbaum Associates, Inc. 
The main idea for chapter two, Nonverbal communication: its origins and development, is the awareness of events around the child such as gaze and gesture interaction, facial expressions, and modifying emotional expressiveness. "With age, children's encoding (sending messages) and decoding (interpreting messages) skills increase. Yet children are better at decoding than at encoding, a fact suggesting that nonverbal comprehension precedes production" (Haslett, B. B., & Samter, W., 1997, p. 35). This fact represents interpersonal communication and how it improves with age in children. 
The main point for chapter three, The development of language, is the social development based on the environment of the child. "Children's nonverbal communication skills, especially those developed through interactional synchrony with adult caretakers, foreshadow the conversational exchanges that typify interpersonal communication." (Haslett, B. B., & Samter, W., 1997, p. 57) Good interpersonal communication starts from the beginning with infant communication, mainly nonverbal, and so it translates to the developmental skills to attain high levels of communication. This chapter also touches on stages in language development which is a slight alternative idea to explain parts of interpersonal developmental process. The stages include prelinguistic development, speech perception/production, semantic development, private speech, and first words. 
Also, the main idea for chapter four, Developing verbal communication and how its relevant in children's acquisition of a variety of communicative strategies for attaining goals. A main focus is "discussing the communicative intentionally substage of development" for infants "emerging abilities to control their communicative skills" (Haslett, B. B., & Samter, W., 1997, p. 105). All three chapters contribute to a more concise understanding of language how it contributes to the ideas of interpersonal communication development in young children.