Young children are thought to be vulnerable to separation from their primary caregiver. This raises concern about whether early childcare enrollment may harm child development. We use childcare assignment lotteries to estimate the effect of enrollment at age 1–2 on cognitive development in Norway. Estimates show significant gains in language and mathematics at age 6–7 and a substantial drop in scores below publicly set thresholds for low performance. Across subsamples, we find a pattern of stronger effects on underperforming groups. We find little support for childcare quality or family income as drivers of our results.

This paper develops a criterion to assess equalization of opportunity that is consistent with theoretical views of equality of opportunity. We characterize inequality of opportunity as a situation where some groups in society enjoy an illegitimate advantage. In this context, equalization of opportunity requires that the extent of the illegitimate advantage enjoyed by the privileged groups falls. Robustness requires that this judgment be supported by the broadest class of individual preferences. We formalize this criterion in a decision-theoretic framework and derive an empirical condition for equalization of opportunity based on observed opportunity distributions. The criterion is used to assess the effectiveness of child care at equalizing opportunity among children, using quantile treatment effects estimates of a major child care reform in Norway. Overall, we find strong evidence supporting equalization of opportunity.