This study examines the relation between principals' leadership and teachers' organizational commitment, mediated by distributed leadership. Data were collected from 1,495 teachers in 46 secondary schools. Structural equation modeling indicated that the effect of principals' leadership on teachers' organizational commitment is mediated by the leadership of assistant principals and teacher leaders, cooperation within the leadership team, and participative decision making of teachers. Therefore, principals should stimulate assistant principals and teacher leaders to take part in leading the school, lead the school in a collegial way with other members of the leadership team, and empower teachers to participate in school decision making.