This case study enabled researchers to understand the knowledge embedded in a world language teacher's enactment of content-based instruction (CBI) through the lens of a theoretical model inspired by Shulman's (1987) construct of pedagogical content knowledge (PCK). The model, called integration pedagogical content knowledge (I-PCK), represents an adaptation of PCK that explicitly addresses the expanded set of content knowledge that is necessary for teachers to effectively implement CBI. Through descriptions of the participant's knowledge and experiences, the case study documents the I-PCK model in action, highlighting her strengths when integrating both academic content and world language learning and allowing specific areas that were in need of further development to be pinpointed. Findings suggest that the model can inform the work of language teacher education and professional development focused on CBI.