The authors study the relationship between child work and cognitive development in the four Young Lives countries. They address a key weakness in the literature by including children’s full time-use vector in the analysis, which leads to different findings from previous studies which do not distinguish between alternative counter-factual activities. They find child work is only detrimental if it crowds out school/study time rather than leisure. Furthermore, the marginal effects of substituting domestic chores or economic activities for school/study time are similar.