Teacher leadership studies have identified attributes of teachers who assume leadership roles. This study expands the literature by adding the theoretical frame of collective efficacy. The Teacher Leadership Inventory and the Teacher Efficacy Belief Scale-Collective were administered in two states to 1193 teachers in 50 schools; 719 teachers completed the surveys. Findings indicate a strong relationship between a faculty's collective efficacy and the extent of teacher leadership in a school. The exception to this relationship is the finding that principal selection of teacher leaders is negatively correlated with teacher leadership.