The purpose of this study is to find evidence to promote interaction in cooperative learning. To this end, the contents of the interaction rules voluntarily suggested by learners were examined, and the learners' perceptions of the effectiveness of the interaction rules were analyzed. The data for this study included group activity rules voluntarily set by learners in cooperative learning classes conducted by the researcher over an eight semester period beginning in 2016 and ending in 2019. The learners set five categories of rules for learning effectiveness in cooperative learning: First, rules for active participation, second, rules for ensuring fairness, third, rules for respecting members, fourth, rules for establishing intimate relationships with members, and finally penalties for breaking the rules. The results showed that the rules had a positive effect in connection with the objectives set initially. It was reported that the rules gave formality to group activities to encourage active participation, and helped maintain fairness due to their increased accountability for the implementation of the rules. Moreover, the learners responded that by applying the rules of consideration and respect for the group members, they were able to establish a closer relationship with their group members. The negative effects of the use of interaction rules, however, need to be addressed in order to improve compliance by learners and allow for appropriate intervention by the instructor. This study is meaningful in that it reveals the basis for effective cooperative learning strategies from the learners' point of view.