This study investigated the role of gesture in communication development. Gestural categories, based on communicative function, were identified from longitudinal videotapes of one mother-child pair. The videotapes were made weekly or bi-weekly from the time the child was 13 months of age until she was 42 months of age. The results of the study indicated that gestures can be reliably delineated. In addition, the gestures served a number of communicative functions: (1) attention directing, (2) referent specifying, (3) requesting information or action, (4) supporting the verbal message, and (5) answering yes/no questions. Although the pair's activity influenced the gestural category utilized, a developmental pattern emerged. As the child's linguistic sophistication increased, the mother's use of gestures decreased and the child's increased. The results are discussed with respect to the available literature. (Author/AMH)