This qualitative case study examined the process of change in an experienced elementary teacher's belief structure during implementation of an inquiry-based science program. Difficulties generally associated with ascertaining beliefs were minimized by using Leatham's ("Journal of Mathematics Teacher Education," "9," 91-102 (2006) Sensible System Framework, enabling researchers to obtain rich descriptions of the teacher's belief structure by focusing on words (professed beliefs), intentions (intended beliefs), and actions (enacted beliefs). Models were constructed of the teacher's belief structure before and after implementation of the Science Writing Heuristic (SWH) approach (Hand et al. International Journal of Science Education, 26(2), 131-149, 2004), an inquiry-based approach to teaching science. Key beliefs for this teacher were related to how students learn, goals for teaching science, focus of instruction, and roles of teacher and student. Ultimately, the teacher shifted her professed, intended, and enacted beliefs resulting in a shift from a teacher-centered to a student-centered classroom. Findings support Thagard's Coherence Theory of Justification (2002), positing that change in one belief creates a state of disequilibrium that must be alleviated by changing/realigning other beliefs in order to re-establish coherence in the overall belief structure. This research focus is distinct from the general trend in teacher beliefs research in important ways. Most significant is that this study was not focused on the traditional two lists--those beliefs that were consistent with practice and those that were inconsistent with practice--but instead focused on the entwined nature of beliefs and practice and have shown that a teacher's practice can be viewed as their enacted beliefs, an integral part of the teacher's overall belief structure.