Teachers generally experience a decline in self-efficacy levels during a curriculum change, and Georgia converted from a Quality Core Curriculum (QCC) to Georgia Performance Standards (GPS) the last several years. Middle and high school math teachers experienced an annual tiered rollout of the mathematics curriculum, and this qualitative study was conducted to determine the impact that curriculum changes and implementation had on teacher self-efficacy (TSE) levels. Six middle school and six high school mathematics teachers were interviewed to determine the phenomenological impact that these changes, implementation, and subsequent professional development opportunities had on teacher self-efficacy levels. While the four main forces of mastery experiences, modeled learning, verbal persuasion, and emotional arousal can be embedded into professional development opportunities to minimize the negative impact of curricular changes on TSE, middle and high school mathematics teachers in a metropolitan Atlanta school district reported that professional development opportunities fell short of providing mastery experiences and modeled learning that could have repaired the damage created by the curriculum change and implementation. The lack of teacher involvement in the process, the rushed nature of the implementation, the lack of aligned textbooks to support the new curriculum, and the perceived lack of opportunities to develop student mastery of the standards given the abbreviated instructional timelines contributed to decreases in teacher self-efficacy levels. Based on these findings, further research is needed to determine the best practices involved in changing and implementing a curriculum. Based upon input from teachers regarding their instructional and training needs, results could be applied to teachers across all grade levels and content areas. [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.]