Abstract: The general goal of the present study is to analyze whether children with siblings lag behind their only-child counterparts in terms of health and nutrition, cognition and educational performance, and non-cognitive outcomes. We draw on a dataset containing 25 871 observations constructed from three school-level surveys spanning four provinces in China. The analysis compares children with siblings and only children aged 9 to 14 years old in terms of eight different health, cognitive and non-cognitive indicators. We fi nd that with the exception of the anemia rate, health outcomes of children with siblings are statistically indistinguishable from those of only children. In terms of cognition, children with siblings performed better than only children. Moreover, outcomes of children with siblings are statistically indistinguishable from those of only children in terms of the non-cognitive outcomes provided by measures of anxiety. According to our results, the same general fi ndings are true regardless of whether the difference between children with and without siblings is disaggregated by gender.