This study was one of four designed to develop the methodological, measurement, and research strategies necessary to begin to define, analyze, and understand cooperative behavior among 4- to 6-year-old children in educational settings. Subjects were 30 4-, 5- and 6-year-olds in a kindergarten program. Each of the 30 children was observed for a 20-minute period during "center time", i.e., the period during which each child joins in the activities of one or more of the 10 learning centers. A Cooperative Behavior Checklist (CBC) was developed to provide information concerning: (1) an account of the antecedent conditions in which cooperative behavior is taking place, provided by either teacher or child; (2) the flow of cooperative behavior, either verbal or nonverbal; and (3) the behavioral outcomes. Results of the study suggest that it is possible to develop observational techniques that can reliably record the antecedent conditions, flow, and outcome behaviors which make up the sequence of behaviors described as cooperation. The appendix contains a complete description of the CBC instructions, the code sheet, and a detailed presentation of the results. (CS)