Proviso Mathematics and Science Academy (Forest Park, IL). The school’s administration believes in “Teacher Leadership in Exchange for Accountability.” A team of teachers worked with administration to develop a project to build teacher leadership capacity through three activities. The activities include: distributive leadership through the development of a School Leadership Team, introduction of grade level lead teachers, and teacher-led professional development. Teacher-led professional development substantially built the capacity for teacher leadership. Teachers interested in leading professional development, aligned with school goals, had to submit a written proposal to the principal at least five weeks prior to the proposed activity. PMSA administration and department chairs provided general oversight, scheduling, and monitoring of the effectiveness of the teacher-led professional development. These activities led a successful translation to school goals and instructional growth plans that included research-based best practices and data analysis. The project’s effectiveness was measured by positive evaluations, optimized teacher participation, and strong gains on teacher leadership indicators on the 2017 Illinois 5 Essentials Survey. PMSA has deduced that teacher collaboration is the most powerful form of professional development. The project accomplished its ultimate goals: increase teacher efficacy and create a healthier overall school culture that leads to increased student growth and academic achievement.