The purpose of this study was to examine the process through which high school mathematics teachers direct their own learning and professional growth. Improving our understanding of the process of self-directed learning has significance in the field of mathematics education due to the degree to which the Common Core State Standards movement has changed classroom content and instructional culture. This study followed a group of high school teachers as they worked on improving their pedagogy and adapting to changes in curriculum and to the practice of mathematics in the classroom. The interconnection model of professional growth was used as the framework for the study. This model captures the iterative process of learning over time through the categorization of change into external and internal domains, a domain of practice, and a domain of consequence. The results of the study confirm the utility of the model in capturing the growth process and adds the observation that much of the exchange of ideas is taking place during professional conversations. The study includes recommendations for how school leaders can promote growth and suggestions for further research to determine which growth strategies are optimal. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]