This qualitative case study explores how one secondary world history teacher, teaching in a high-stakes testing context in a district pushing teachers to utilize differentiated instruction, makes sense of this pedagogical approach. We examine teacher sense-making within a conceptual framework of policy realization and ambitious teaching and learning. The teacher made no claims to being an expert on differentiation; yet, the findings indicated that she did possess an understanding of differentiation congruent with the literature and, whether she recognized it or not, used many strategies suggested by Tomlinson and other experts on differentiation. Her thinking about differentiation also appeared to be shaped by relational and contextual issues. Stated differently, the Virginia Standards of Learning exams and the pressure from administration for high pass rates appeared to shape how the teacher thought about her students, her content, her instruction and, ultimately, her approach to differentiation.