Research indicates that students’ experience of belonging, including close relationships with school social groups, individuals, and activities, significantly facilitates motivation and achievement with distinct patterns for students of different ethnic groups. However, there is a lack of clarity and understanding regarding what constitutes belonging and the role it plays in students’ motivation and achievement for diverse groups. This study attempted to address these issues, by examining students’ perceptions of their sense of school belonging in four areas: bonding with teachers, having a place within the network of peer relationships, extracurricular involvement, and perceived ethnic-based discrimination. Additionally, the extent to which these four dimensions explained student belonging and the degree to which belonging accounted for the relationship between motivation and achievement for African-American, Asian-descent, Latino, and European American adolescents were examined. Data were obtained from a larger study of 9th -12th grade students attending seven ethnically diverse high schools, six in California and one in Wisconsin. Respondents included: 580 African-American, 948 Asian American, 860 Latino, and 3,142 European American students. All four measures of belonging were significant for European American and Latino students. The results capture the critical role of belonging for motivation and achievement in a way that respects the complexity and diversity of the lives of students. The importance of genuine engagement in multiple social systems within the school for students from four distinct ethnic groups was underscored. Figures, tables, references