Language teacher identity (LTI), and its essential component, teacher agency, are inextricably intertwined with emotion labour. This qualitative case study explored how the agency and LTI of an early-career Iranian female teacher of EFL (English as a foreign language) were affected by her engagement in emotion labour in two public schools. Data in the form of class observations and semi-structured interviews were collected, focusing on the emotional episodes of the participant’s practice at her previous and current workplaces, and then analysed through grounded theory procedures. The findings revealed that while the favourable emotional atmosphere of the first school helped the novice teacher to be at ease with her LTI, growing emotion labour caused by the deep-seated contradictions in the second school eroded her sense of agency and made her give her current job affiliation a second thought. Implications and suggestions for further research are discussed.