The goal for this study was to better understand how an ambitious teacher uses pedagogical content knowledge while planning learning environments that focus on disciplinary, inquiry-based practices in world history. We used Monte-Sano and Budano's (2012) framework for pedagogical content knowledge for teaching history to examine the teacher's planning over the course of a year. Through interviews and analysis of artifacts, we found more specific sub-categories that represent the various ways that the teacher thought about transforming, representing, framing, and attending (...) to students’ ideas about world history. Additionally, we found a hierarchical relationship in the aspects of the teacher's pedagogical content knowledge that aligned with her phases of planning (skeletal, unit planning, reflective) throughout the year. These findings highlight content-specific issues in planning world history courses—particularly those focused on the earliest eras—including questions about how teachers can find appropriate resources, organize world history content for teaching, and help students understand world historical narratives. We conclude with a discussion of these issues and implications for teacher education, curriculum design, and further research. (shrink)