The purpose of this case study was to examine the instructional approach of a highly successful Advanced Placement Music Theory teacher. I visited the participant's class twice a week for 14 weeks, taking field notes, conducting interviews, and collecting instructional artifacts. Analysis of qualitative data revealed three main themes: classroom atmosphere, instructional strategies, and the Advanced Placement exam. The participant's classroom atmosphere was built on effective pacing, student rapport, and an active, open learning environment. His instructional strategies included offering individual attention to students, asking questions to model thinking, and connecting sight to sound. He used the Advanced Placement exam as both an instructional guidepost and motivational tool. Implications for music educators include the need to focus on specific approaches conducive to successful theory teaching, which may share both similarities and differences with approaches they use when directing ensembles.