An unacceptable number of learners in under-resourced schools in South Africa are failing to perform adequately in national and international benchmark tests. Poor learner performance has been linked to poor-quality teaching, which, in turn, can be attributed in part to a lack of instructional leadership at schools. According to policy, heads of department (HODs) are best placed to offer such leadership, but in many schools this is not happening. We explain how we engaged HODs in one such school in a participatory action research process, to help them construct a framework for improving their instructional leadership. Qualitative data was generated through open-ended questionnaires, transcripts of recorded action learning set meetings, photovoice narratives, and reflective journals, and these were thematically analysed. The action learning framework developed by the participating HODs, while not being a definitive answer to improving the quality of teaching and learning, may provide guidelines for other HODs to improve their own instructional leadership practices. Since it is a process-based model, application of the model as an approach to improve instructional leadership could prove beneficial in both well-resourced and under-resourced contexts.