<p>Previous studies have found significant inequality of opportunity (IOp) in cognitive skills(such as academic achievement). This study extends the analysis to explore inequality of opportunity in social and emotional skills based on the 2019 Organization for Economic Co-operation and Development’s (OECD) Study on Social and Emotional Skills (SSES) data and Roemer’s theoretical framework. Our findings indicate that (1) the level of inequality of opportunity in social and emotional skills(or non-cognitive skills) varies widely, with the highest levels seen in Suzhou (China) at 33.75% and the lowest in Houston(the U.S.) at 13.01%. These disparities surpass the levels of cognitive inequality reported in previous literature. And in each city’s sample, the inequality of opportunity within the agreeableness dimension is markedly larger than in the other four dimensions. (2) Across most regions, the inequality of opportunity in social and emotional skills is more pronounced among 10-year-olds compared to 15-year-olds. (3) The study highlights that the number of family books, parenting style, and school environment are the three key determinants that shape students’ social and emotional development.</p>