Research has found the Social Judgment Analysis (SJA) approach, with its focus on judgment policy and cognitive feedback, to be a significant factor in developing group member agreement and improving member performance. A controlled experiment was designed to assess the relative quality of the judgment making process provided by SJA. Undergraduates (N=144) were clustered into 32 groups on the basis of systematic differences in their judgment policies to assure heterogeneous groups with members in initial disagreement. Twelve of the groups used SJA to form a group policy to predict horse race outcomes; the remaining 20 groups, as well as 38 individuals, were assigned to four control conditions with variations in task-related instructions and cognitive feedback. Quality of group decisions, reduction of group disagreement, and participant rating of group process were assessed. Results indicated that the SJA approach with task-related instructions and cognitive feedback concerning individual judgment policies mutually shared by the entire decision-making group not only produced extremely high levels of group consensus, but also permitted individual members to learn and improve their own performance. The findings suggest that alterations in the content of interpersonal communication such as those provided by the SJA approach make a significant difference in group effectiveness. (NRB)