To reduce the high repetition rates in early years of primary school, the government of Cambodia piloted a school readiness program (SRP) in the first two months of Grade 1 of primary school.This study examines whether such intervention has effects on students’ immediate acquisition of school readiness skills as well as students’ longer term achievement of formal curriculum. The study finds that children who participated in SRP outperform children that did not participate in both outcomes, controlling for pretest score and background variables. The findings suggest that the intervention may be one alternative model to preschools in countries where access to pre-primary education is limited.