Early home learning activities such as book reading and playing with number toys are expected to impact children's development. However, isolating the effects of these activities is challenging due to the correlation between parental engagement and socioeconomic background, which influences how children are raised and supported. Even longitudinal studies can be distorted by this correlation. Therefore, we adopt an alternative approach and relate differences in early home literacy and numeracy activities to differences in later reading and math performance. Applying this approach to data from 37 countries suggests an overall positive effect of early home learning activities on achievement in fourth grade. Given their lower prevalence in disadvantaged households, targeted policies supporting parental engagement may help reduce socioeconomic achievement gaps.