This study provides new evidence on school efficiency for low and middle income countries. We use data from PISA for Development (2017) for seven countries to obtain estimates on school efficiency using data envelopment analysis, both for cognitive and non-cognitive outputs, and their determinants. We find that there is a scope to increase efficiency by 20–22% via boosting both types of educational outputs and by reducing within-country disparity on schools’ efficiency scores by weakening the impact of students’ disadvantages. Our results suggest that schools cognitive inequality can be reduced alongside inefficiency. Cross-country results suggest similar drivers of efficiency across countries, at least for students’ school determinants, though we find more nuanced results on teachers and policies determinants for efficiency.