Teachers in high-poverty middle schools need additional supports from administrators to build collective teacher efficacy. Supportive leadership is the driving force in leading collective teacher efficacy in high-poverty middle schools. A qualitative, instrumental case study was utilized to explore how teachers perceive administrative supports that foster collective teacher efficacy in the context of a high-poverty middle school. The study found supportive leadership as a critical indicator of building collective teacher efficacy in high-poverty middle schools, specifically the leader's visibility as a primary support of collective teacher efficacy. Additionally, the study found supportive leadership as the driver of collective teacher efficacy with goal consensus, empowered teachers, embedded reflective practices, and cohesive teacher knowledge as interdependent factors that foster collective teacher efficacy. The study results found that additional research needs to be conducted on collective teacher efficacy, especially in the context of high-poverty middle schools, and the connection to student achievement. [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.]