The present study serves as a unique contribution to the literature by examining the causal impact of HS attendance using compliance (actual enrollment) and by investigating the factors affecting families’ choice to enroll in HS versus non-HS programs. Specifically, the present study examined for the following hypothesis 1. To estimate the causal impact of HS enrollment on children’s comprehensive outcomes (cognitive, social-emotional, and health) with an instrumental variable (IV) analysis. We hypothesized that HS enrollment improved the outcomes. 2. To investigate why children who were assigned to HS did not enroll in HS but attended other care programs. We estimated the determinants of such a non-compliance to HS assignment. In particular, we hypothesized that the quality of care is associated with the prevalence of non-compliance. (author abstract)