Đặng Tự Ân played a pivotal role in the genesis, adoption, and diffusion of pedagogical and curricular reforms that are transforming teaching and learning in the Socialist Republic of Vietnam. His is a fascinating story of a career that began with the paralyzing disappointment of being assigned to study in a seemingly lowly teacher training college only to culminate, decades later, in his central role in the research, design, piloting, and scaling up of a reform that, despite numerous difficulties, would shape the most far-reaching and progressive curricular reforms in Vietnam’s long educational history. This essay uses the case of VNEN, a pedagogical and curricular reform adapted to Vietnam from the Colombian Escuela Nueva (EN) model, to advance our understanding of the challenges policy entrepreneurs and networks of policy stakeholders can encounter in efforts to institute pathbreaking reforms and of the formidable challenges they can encounter in bringing such reforms to scale. In contemporary research on the political economy of education and learning, the notion of an education system’s coherence for learning refers to the extent to which an education system develops relations of accountability that support improved learning outcomes across a range of relationships that define an education system and an array of policy design elements that education policies contain (Pritchett 2015, Kaffenberger and Spivack 2022). In the development literature, the notion of iterative adaptation speaks to a process wherein the performance of policies can improve rapidly through experimentation rather than mechanical transplantation of “best practices” (Andrews et al. 2013, Le 2018). From the standpoint of research on education systems and major reform efforts aimed at enhancing learning, the case of VNEN represents a particularly interesting instance of the innovation of pedagogical and curricular reforms that were, at their most successful moments, deeply coherent for learning, but which encountered problems at scale owing to a range of factors highlighted in this analysis. More broadly and however problematic at times, Vietnam’s VNEN experience contributed to the broad uptake and diffusion of new curricula and teaching practices. This raises questions about what we can learn from VNEN, including its successes and problems, that may have value for promoting continued improvement in Education systems performance around learning in Vietnam and other settings.