This report, the first of a series of three, describes a study of the structure and use of language in a defined type of communication situation. Following a review of psychological, sociological, and linguistic studies dealing with the structure of communication or the structure of discourse, a type of goal-directed (convergent) communication is defined in which consisten patterns of language use are expected to occur. The language of 48 dyads of children and 24 dyads of adults was observed in three standard convergent communication situations and used to develop a system for analyzing the verbal interaction. This sytem defines the structural units of the communications and permits a description of the behaviors, the connecting structural relationships, and the content which occur in and between utterances during the communication process. Appendices contain a manual used to instruct coders in the use of the system and the estimates of inter-judge agreement obtained with the manual. (Author/JM)