Background: The first three years of life are the critical and sensitive periods for the formation of individual abilities. However, existing data indicates that early childhood development (ECD) in economically vulnerable areas of China is lagging, which is closely related to the lack of parenting knowledge and poor parenting practices. Methods: We conducted a non-masked cluster-randomized controlled trial in a former nationally designated poverty county of China. All 6–36-month-old children and their caregivers living in 18 communities/clusters (10 towns and 8 districts of the county seat) were enrolled in a 9-month parenting training program. In the treatment-group communities, ECD centers were installed where community workers provided parenting training sessions. If caregivers were unable to visit the center, home-based parenting training was offered. No intervention was provided to the control group. Furthermore, we assigned half of the treatment group to receive monthly developmental feedback in addition to the parenting training. Based on the baseline and follow-up data, we investigated the treatment effects on parenting knowledge, attitudes, and practices through Intention-to-Treat (ITT) and Treatment-on-the-Treated (TOT) analyses. Results: We found no effects on the parenting knowledge and attitudes of the caregivers but significant effects on the parenting practices. The effects were heterogeneous among families with different characteristics. Specifically, on average, the program had the largest effect on internally oriented caregivers, mothers with higher education, and mothers who are primary caregivers. We want to emphasize that, although the ITT effect on parenting practices (the average treatment effect) were stronger for mothers with higher education, the TOT effect on parenting practices (the local average treatment effect, LATE) were stronger for mothers with less education. That is, even though on average the program helped mothers with higher education, but among complier families, the program benefited mothers with less education. Conclusion: The findings indicate that, at least in the short run, the program can directly change caregivers’ parenting practices without changing their knowledge and attitudes. Future studies are needed to investigate whether parenting knowledge and attitudes can change in the long run.

The goal of the present study is to examine differences in cognitive, psychomotor, and social-emotional development scores between only children and children with siblings aged 6–30 months in rural China using data of 1802 children across 351 villages in 174 townships, disaggregating according to child gender. The results indicate that having a sibling is negatively associated with cognitive, psychomotor, and socioemotional development for girls, but not for boys. Despite this, girls appear to be developmentally advantaged compared to boys, even when they have a sibling. Our results, however, are not conclusive regarding why only-girls are affected while boys are not affected by the existence of siblings. Parenting behaviours (such as playing with children, reading to children, reading to children with books, and singing to children), appear to be unrelated to the developmental differences between only-girls and girls with siblings.