In efforts to improve the quality of education, the disparity between policy and practice in implementing learner-centred pedagogy has been well-documented. Acknowledging these challenges, this study investigated active learning reform using design-based research, an interventionist methodology in the Maldives. The intervention specifically sought to address the policy-practice gap through the development of a structured model of active learning, drawing on recommendations in the literature and moving beyond the simple dichotomy of teacher-centred versus learned-centred pedagogy. Teachers' enactment of the model was studied within a Maldivian island school. The data identified enabling conditions in teachers' use of the intervention: the pedagogical model needs to be clearly and simply articulated; promote a staggered approach to reform; and reflect and respect local priorities. These were converted into design principles -- an outcome of design-based research intended to inform the work of others enacting similar reforms.