Distributed leadership in schools is not exclusive to professional learning communities; it is distributed in all schools, for good purposes and for bad, by design and by emergence. In this article, we describe a normative view of distributed leadership that tends to be a leadership of advocacy, and we offer a descriptive perspective that argues that although sustainable leadership is distributed leadership, not all distributed leadership is sustainable leadership. It depends on how the leadership is distributed and for what purposes. Using one of our seven principles of sustainable leadership--breadth--we then show how leadership distribution in professional learning communities is both distinctive and varied. (Contains 1 figure.)