Emotion labor is expecting individuals to display institutionally-accepted emotional behaviors. This study examined the role of school assessment policies in 13 Iranian English language teachers' emotion labor in a private language school. To this end, data were collected from semi-structured interviews and narrative frames. Data analyses revealed three major themes in relation to the teachers' assessment-related emotion labor: Constrained assessment agency, resilience in assessment, and the significance of heeding assessment emotions. The study shows that top-down policies of the school created emotional conflicts for the teachers, yet such policies in turn motivated the teachers to invest more in implementing assessment techniques that respond to their own and students' needs. The findings are discussed in light of contextual particularities of assessment, which are linked to power and dominant discourses shaping teachers' assessment-related emotion labor. Based on the findings, we provide implications for policymakers and teacher educators to pay more focal attention to teachers' assessment emotions and emotion labor.