BackgroundEarly education program (EEP) was created to support parents with 1 to 3 year olds living in poverty situation in Mexico, and includes education and child daycare for 8h five days per week. The objective of this study was to evaluate the association between length of stay in EEP and the level of development in children. MethodsCross sectional, population-based study conducted in two Mexican states. All children aged between 12 to 48 months enrolled in EEP from November 2014 to January 2015 were included. Child Development Evaluation (CDE) test was used to screen early development in every child. Normal early development prevalence odds ratio (OR) was calculated adjusted by gender, impairment and state, using as a reference those children with less than 30 days in the program. ResultsThe study included 3,387 children from 177 EEP nurseries, from which 53% were male; age by group was divided in 12-24 months (22.3%), 25-36 months (37.6%) and 37-42 months (40.1%). Normal development adjusted OR by age was 1.9 (CI95%: 1.30-2.78) for 6-11 months, 2.36 (CI95%: 1.60-3.50) for 12-17 months, 2.78 (CI95%: 1.65-4.65) for 18-23 months and 3.46 (CI95%: 2.13-5.60) for >24 months. By area of development, a greater probability of having a normal result for language and social areas was observed after 6 months in the program, and for motor (both gross and fine) and knowledge areas after 12 months. ConclusionThe length of the stay in the EEP after 6 months significantly and progressively increases the probability of normal development regardless of gender and age.