Identity development is a challenge facing novice TESOL teachers that can threaten their commitment to teaching. This case study looks at multiple identities (Gee, 2000), situated activity systems (Engeström, 2015), and multiple components of organizational commitment (Meyer & Allen, 1991) to explain the identity development of a novice Iranian woman teacher of ESOL in a private language institute in Iran. Over a 12-month period the researchers collected multiple spoken, written, and observed data sets on the teacher's English language teaching and learning experiences. Influences on and turning points in the development of identity and commitment in the workplace are analyzed. The findings show that contradictions in the teacher and the activity system were transcended through actions that developed her identity, which in turn promoted her commitment. Implications and further studies are suggested about the interrelationships among identity, activity systems, and commitment, the kinds of activities that can promote identity development, and women language teachers in the Middle East and Muslim world.