School based leadership is an increasingly complex task that requires leaders to find ways to spread responsibility throughout organizations to achieve goals. This dissertation research is an exploratory study in the field of sustainability of distributed leadership at Capital High School, a large urban high school. Exploring the sustainability of the Annenberg Distributed Leadership Project (DL Project) the author assessed the practices still in use at a single school site to determine what had caused the distributed leadership management structure to sustain and thrive in an environment of budgetary restrictions and staff reduction. The researcher contacted eighteen participants from the DL Project. Ten participants maintained administrative or teaching positions at Capital High School and eight participants had received DL Project training for use at other schools. The participants from Capital High School were asked to complete a survey with open-ended questions and the others were asked to complete open-ended questions and participate in follow-up interviews. All participants from Capital High School responded to the survey (n = 10 reported for survey), seven of the additional participants responded to the open-ended questions (n = 17 reported for open-ended questions), and three participants (n = 3) engaged in follow-up interviews. All participants had completed a master's degree and five had completed a doctoral degree. Respondents had an average of 29.4 years in the field of education. The overall results of the study indicated that relational trust between teachers and the principal and a highly functional leadership team where participants felt safe to voice their opinions were the causes of sustainability. Respondents indicated that participating in the Annenberg Distributed Leadership Project had a lasting impact on their leadership by showing them how to utilize distributed leadership to encourage buy-in, increase productivity, and teacher retention. Further research utilizing the survey tool could provide knowledge about the sustainability of distributed leadership in other schools or organizations. [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.]