Limited professional training regarding elementary social studies content and pedagogy contributes to the reduction of elementary social studies instruction. The purpose of this descriptive phenomenological study was to explore how the experiences of elementary educators during the 2018 Alabama Bicentennial Summer Institutes held in Mobile, Alabama, have contributed to their professional development in social studies instruction. This study sought to understand how the experience of a social studies professional development for elementary teachers contributed to instructional methods, instructional planning decisions, collaboration, and the use of primary sources. Transformative learning theory (TLT) provided the theoretical perspective for understanding how changes in adult learners may occur in a professional development setting such as the 2018 Alabama Bicentennial Summer Institute. Learning in TLT transpires during critical reflection and rational discourse resulting in changes in the frame of reference (Mezirow, 1996, 1997). Principles of phenomenology guided me to realize interrelated themes. I purposefully selected six participants to represent the experiences of Grades 3-5 teachers from multiple districts and systems. The process included professional development, analysis of lesson plans, purposeful selection of participants, observations, interviews, data triangulation, and intense interaction. Data collection and analysis for emergent themes occurred cyclically during the 2018 Alabama Bicentennial Summer Institute activities, classroom observations, lesson plan analysis, and semi-structured interviews. Emerging themes suggested a transformative influence of the 2018 Alabama Bicentennial Summer Institute experience on the participants' classroom instruction, instructional planning, and use of primary sources. [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.]