Abstract. Integrating theory and research on values, diversity, situational strength, and team leadership, we proposed that team leadership moderates the effects of values diversity on team conflict. In a longitudinal survey study of national service teams, we found significant, but opposite, moderating effects of task-focused and person-focused leadership. As predicted, task-focused leadership attenuated the diversity–conflict relationship, while person-focused leadership exacerbated the diversity–conflict relationship. More specifically, task-focused leadership decreased the relationship between work ethic diversity and team conflict. Person-focused leadership increased the relationship between traditionalism diversity and team conflict. Team conflict mediated the effects of the interactions of leadership and values diversity on team effectiveness.