Identifying and implementing change strategies that create lasting improvement at scale is the holy grail of education reform in populous low/middle income countries such as Nigeria. ESSPIN’s theory of change asserts that sustainable school improvement is possible at scale if implemented through a whole systems approach where inter-connected factors complement each other and the programme works strategically through all three levels of government. To this end key partnerships were formed early in the programme with a joint commitment for change. Interventions were designed around robust evidence of educational gaps as well as individual state’s needs and available resources. A pragmatic approach to implementation was adopted which recognised budget and capacity constraints and allowed phased implementation of School Improvement Programme components. A nimble environment was created whereby education stakeholders were able to learn, adapt and build upon and steer progress specific to their context. In recognition that the quality, pace and longevity of improvement is down to people within the system, ESSPIN prioritised ongoing capacity development of stakeholders at all levels. In a concerted effort to take school improvement to scale, ESSPIN and partners impacted 6.2 million children, over 100,000 teachers and 16,000 schools.