This study addresses lack of student engagement in large English as a second language (ESL) classes at a Pakistani university, using cooperative learning within the framework of participatory action research. A reconnaissance of the literature and thorough situation analysis led to an initial plan based on two cooperative learning strategies: Student-Teams-Achievement-Divisions and Think-Pair-Share. Over a semester, a second-year undergraduate compulsory ESL class was delivered as a series of mini action-research cycles refining this plan. The intervention was evaluated using classroom observation, student questionnaires and semi-structured group interviews. The results indicate that cooperative learning enhanced students' behavioural, cognitive, and emotional engagement relative to their previous experience of learning in lecture-style classes. In addition, the study demonstrates that action research can be used by individual practitioners in even highly problematic teaching environments as a way of emancipating themselves and their students from the helplessness associated with institutional and cultural constraints.