Evaluating social change programs requires methods that account for changes in context, implementation, and participant experience. We present a case study of a school-based partner violence prevention program with young people, where we conducted 33 repeat interviews with nine participants during and after an intervention and analyzed participant trajectories. We show how repeat interviews conducted during and after a social change program were useful in helping us understand how the intervention worked by providing rich contextual information, elucidating gradual shifts among participants, and identifying aspects of the intervention that appear to influence change. Long-term effects of social change interventions are very hard to quantify or measure directly. We argue that a qualitative longitudinal approach provides a way to measure subtle changes that can serve as proxies for longer term impacts.