This paper uses three waves of longitudinal data to examine the impact of expanding access to preschool services in rural areas of Indonesia on two cohorts of children. One cohort was children aged 4 at the start of the project and was immediately eligible for project-provided services when they began operation in 2009. The other cohort was children aged 1 at the start of the project and became eligible for project-provided services two years later. The paper presents intent-to-treat estimates of impact in the short term (first year of the project) and medium term (three years after the project started), using experimental and quasi-experimental methods. For the cohort of 4-year-olds, while the magnitude of the enrollment impact is similar across children from different backgrounds, the impact on child outcomes is larger for children from more disadvantaged backgrounds in the short and medium terms. However, for this cohort of children, it seems that project-provided playgroups encouraged substitution away from existing kindergartens, suggesting that future interventions should incorporate such possibilities into their design. For the average child in the younger cohort, the project led to improvements in physical health and well-being as well as language and cognitive development. For this cohort, there is little evidence of differential impact. This can be explained by the fact that children who enrolled soon after the centers opened (the older cohort) were generally poorer, compared with children who enrolled later (the younger cohort). This may be because of fee increases in project centers as project funding ended.