The Study of Social and Emotional Skills (SSES) is an international effort led by the Organization for Economic Co-operation and Development (OECD) with Houston Independent School District (HISD) serving as the only U.S. site. Over 6,400 10-year-old and 15-year-old students from 119 HISD campuses participated in SSES in the fall of 2019. This brief examines how the characteristics of students' school, peer, familial, and neighborhood contexts were connected with their social and emotional skills. Social and emotional (SE) skills refer to the process by which children acquire and effectively apply the knowledge, attitudes, and skills necessary to understand and manage emotions, set and achieve positive goals, feel and show empathy for others, establish and maintain positive relationship, and make responsible decisions (OECD 2015). SE skills develop within the contexts and the complex networks of social relationships that children experience. This study found that students reported higher social and emotional skills when they perceived higher levels of sense of belonging at school, less bullying at school, and better relationships with friends, family and neighbors. [For Briefs 3A and 3B in this series, see ED626835 and ED626836, respectively.]