This study presents the results of a phenomenological qualitative investigation into the new role of teachers serving as team leaders in a professional learning community, as well as the support team leaders need from members and principals to be effective. Collaborative teacher teams in 6 schools that have been developing as professional learning communities were administered the Group Development Questionnaire (Wheelan, 1994) to determine their level of functioning as a team. Then, focus group interviews with team leaders and team members from both high-functioning and low- functioning teams, as well as principals, were conducted to identify patterns and themes related to the topics of interest. Follow-up interviews with 4 individual team leaders and 1 principal were conducted to verify and clarify ideas that emerged from the focus group sessions. Analysis of the interview data indicated that the role of the team leader involves 4 major areas: (a) building trust, (b) facilitating effective conflict resolution, (c) structuring meetings for success, and (d) acting as liaison with administration on behalf of the team. The actions of the team leader have a clear effect on team functioning, and this definition of leader responsibilities has been a significant but missing ingredient for the leaders interviewed. Support needed from team members includes supporting the vision of collaboration to improve student learning and committing to the team, its leader, and its decisions. Committing to the team and its leader is a function of the respect teammates must have for one another in the collaborative process. Finally, support from principals includes casting a well articulated vision and communicating defined expectations for teams. It is important for the principal to select the right team leaders and work with them to monitor team progress and set the direction for the school. Support also involves providing support for both the team and the team leader through validating the team leader role, providing training and resources, offering feedback on team functioning, rendering advice and guidance on team issues, holding teams accountable, and being flexible during the learning process. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]