Using a large dataset of around 500,000 students from about 1,900 schools, this paper shows the effect of two school closures and 1.5 years of the COVID-19 pandemic on standardized learning growth for mathematics, reading, and spelling in Dutch primary education. We find that the school closures have a negative effect on standardized learning growth, amounting to an annual average of 5.5 weeks of learning loss. When analyzing differential effects by socioeconomic status, parental education, household income, household structure, household size, and migration status, we find that the negative effect is larger for the more vulnerable students