This study examined the relationships between leadership practices of principals and strength of schools as sustainable professional learning communities. Strength of schools as professional learning communities was measured using the Professional Learning Communities Assessment; leadership practices were measured using the Leadership Practices Inventory both Self and Observer protocols. Findings indicated that neither principal's self-perceptions of their leadership practices nor teachers' assessments of their principals' leadership practices were related to strength of schools as professional learning communities. Findings did indicate ten specific leadership behaviors of principals that appear to be more highly related to strength of schools as learning communities. Further analysis which focused on the two strongest learning community schools and the two weakest learning community schools indicated that three specific leadership behaviors within Kouzes and Posner's practices of modeling the way and enabling others to act appear to be the most strongly related to reculturing schools as sustainable professional learning communities. Principals who set a personal example of what they expect of others are most likely to lead schools that function as strong learning communities. Additionally, principals who build consensus around a common set of values are also most likely to lead strong learning communities. Finally, principals who develop cooperative relationship with co-workers are most likely to lead schools that function as strong learning communities. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]