Despite the growth of research on English for specific purposes (ESP) teachers over the past two decades, the scope of research that focally examines ESP teachers' emotions is limited. The present study explored 10 Iranian ESP teachers' emotion labor. Collecting data from questionnaires, narrative frames, and semi-structured interviews, we show how contextual discourses, policies, and expectations of ESP instruction interact with the teacher participants across four areas of pedagogy, assessment, materials, and curriculum and culture. Our findings indicated that content featured as a significant factor in the teachers' emotions, agency, and identity directly, indirectly, and specifically through content-related discourses and participants. More specifically, it is not necessarily the content itself that along with language shape ESP teachers' professional sense-making; rather, the way content manifolds in institutional work and interacts with language through various contextualities, modalities, and participants functions more profoundly in ESP teachers' work. We provide implications for ESP teachers to draw on their collegial potentials to form communities of practice that positively contribute to their professional growth and transform their negative emotions into mutual emotionality.