Thirty-two subjects of simple and 32 subjects of complex conceptual structure participated as decision-making dyads in an experimental simulation. The dyads were exposed to increasing failure or increasing success. The effect of failure and success on subjects' estimates of causality for their "current situation" and its effect on interpersonal attitude within the group were investigated. It was found that subjects take increasingly more credit for success as success increases, but do not take similar credit for increasing failure. It was found that attitudes toward other group members become more favorable when the group is credited with success. Attitudes remain constant when causality attributions show constancy (failure). The effect of success and failure on attribution of causality, and with it the effect on attitudes, was more pronounced for simple than for complex subjects.