The present study was designed to produce novel theoretical insight regarding how leader humility and team member characteristics foster the conditions that promote shared leadership and when shared leadership relates to team effectiveness. Drawing on social information processing theory and adaptive leadership theory, we propose that leader humility facilitates shared leadership by promoting leadership-claiming and leadership-granting interactions among team members. We also apply dominance complementary theory to propose that team proactive personality strengthens the impact of leader humility on shared leadership. Finally, we predict that shared leadership will be most strongly related to team performance when team members have high levels of task-related competence. Using a sample composed of 62 Taiwanese professional work teams, we find support for our proposed hypothesized model. The theoretical and practical implications of these results for team leadership, humility, team composition, and shared leadership are discussed. (PsycINFO Database Record