A study was conducted to investigate developmental aspects of the logical organization of reasons among 30 boys and girls from each of the first, sixth, and tenth grades. Participants were administered the Responsibility Story Test, a measure consisting of stories portraying moral dilemmas and corresponding semistructured interview schedules. Interview questions requested justification for subjects' judgments of what story protagonists should and must do. Subjects' responses were classified as instrumental or normative. Additionally, subjects' elaboration of their basic premise by offering subsidiary information was assessed, complexity of arguments was rated, and the number of simple clauses in each response was calculated. Results indicated that tenth graders gave more arguments and were more likely to include explicit reference to contrasting or alternative arguments than were sixth and first graders. Tenth graders also qualified their inference rules by explicitly stating more contextual constraints on the application of the rules. Sixth graders produced longer reasons than did first graders. Elaboration among sixth graders was similar to that of tenth graders in amount and kind, but, while sixth graders gave more complex reasons than did first graders, their reasons were not as complicated as those of tenth graders. First graders gave essentially single-premise reasons. They were able to use both instrumental and normative logical schemata, but they included virtually no complex argumentation or elaboration of premise. (RH)