This study aims to identify the effect of attending an enhanced-quality preschool program on students’ emergent math, emergent language and literacy, socio-personal skills and knowledge of health, hygiene, nutrition and safety. We used a quasi-experimental design with pre-post measures and two control groups, with data from a random sample of approximately 709 4–6-year-old children in 40 villages and 5 districts of Bangladesh. Controlling for demographic and baseline characteristics, we compared the outcomes of children who attended an enhanced-quality preschool with the outcomes of children who lived nearby, but were (1) not attending preschool or (2) attending a standard-quality government preschool. We found that, after controlling for baseline characteristics, initial pre-test differences that significantly favored children in enhanced-quality preschools over non-preschoolers significantly increased over time in all outcomes of interest. We did not find differences at baseline between children in the enhanced and the standard-quality preschools, but after the intervention, preschoolers in the enhanced program gained small and positive advantages over their counterparts, which were not statistically significant, possibly due to the sample size of the Government Public School group, which made us unable to detect effects sizes smaller than 0.25 standard deviations. We discuss implications, threats to validity and future research.