Professional learning for teachers requires an immense amount of time and resources, but it often shows varying efficacy in terms of shifting teacher practice or impacting student growth. Studies have identified the characteristics that lead to more impactful professional learning experiences. In Cycle 1 research, this study began by asking teachers to describe significant learning experiences in their professional careers and experiences or events that made them curious about their own practice. Using findings from the Cycle 1 data, the researcher collaborated with other stakeholders in a K-12 independent, international school to design a framework of professional learning to help teachers in creating a more equitable learning experiences and environments that result in deeper learning for students. During this action step, teachers engaged in a process of collaborative inquiry in which they used student data to determine a shared question of practice. They then collaborated in a process of professional learning, shared design of lessons and assessments, and chose instructional strategies. Throughout this process, the researcher interviewed teachers, teacher leaders, and the instructional coaches. From this data collection as well as the relevant research, three primary findings emerged: the pivotal role of teacher leaders, the opportunities and challenges of data, and the importance of recognizing and honoring landmarks within the process of change. [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.]