In this study, we first operationalized distributed leadership. Multilevel confirmatory factor analyses showed that distributed leadership can be defined from different dimensions: quality and distribution of support and supervision performed by the leadership team; cooperation within this team; and participative decision making. Second, the relation between dimensions of distributed leadership and teachers' organizational commitment was investigated. Multilevel analyses on data from 1,522 teachers in 46 secondary schools indicated that 9% of the variance in teachers' organizational commitment was attributable to differences between schools. Further, the analyses revealed that it is not the distribution of leadership functions among formal leaders that plays a key role in teachers' organizational commitment. The perceived cooperation within the leadership team and the quality of their support are crucial.