In this study, reasoning about moral responsibilities in friendships on the part of 97 subjects was assessed at the ages of 7, 9, 12, and 15 years. Assessment was undertaken of: (1) general reasoning about the moral obligation of promise keeping; (2) general reasoning about responsibilities in friendship; and (3) situation-specific reasoning about promise keeping and close friendship in a conflict between best friends involving promise keeping. Interview data were collected and analyzed. Results indicated that knowledge about promise keeping develops before a general understanding of closeness in friendship. Promise keeping is used as both a practical and a moral reason in decision making from an early age. Friendship is used as a practical reason from an early age, while its use as a moral reason develops later. There was a marked developmental trend towards establishing consistency between moral judgment and action choice, which peaked at age 15. A list of 15 references is included. (BC)