This qualitative case study addressed the problem of teachers at an International Baccalaureate Primary Years Programme (IBPYP) site attempting a change to instructional practice without participation in a site-embedded professional development plan specifically designed to support a change in practice. The purpose of this study was to explore the perceptions of the participants about professional development experiences in terms of how the experiences affected and supported a change in pedagogy. A qualitative case study design was employed within a purposeful sample of 10 teachers from an IBPYP site. The conceptual framework included components of effective professional development and multiple theories of learning. The central research questions focused on describing how teachers at an IBPYP site engaged in professional development. Data were collected from face-to-face interviews, surveys, IBPYP planner documents, and professional development attendance documents. Data coding employed typological analysis based on the components of effective professional development outlined in the conceptual framework, followed by inductive analysis of the data. Findings showed that some essential components of effective site-embedded professional development were not being experienced by the study participants. A recommendation is that district, IBPYP site administrators and IBPYP teachers recognize the problem described by this study and work to ensure teachers are experiencing a complete cycle of site-embedded professional learning. The findings could affect social change when it becomes the teachers at the site who are empowered with documenting the design, implementation, observation, and reflection of effective practices in inquiry teaching and how those documented changes affect student achievement. [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.]