The purpose for this study was to examine the structure and construct validity of a measure of ethnic identity among young adolescents from diverse ethnic groups. Students in sixth, seventh, and eighth grades (N = 5,423) from diverse ethnic groups completed the Multigroup Ethnic identity Measure (MEIM) measures of psychological well-being and a measure of salience of ethnicity. Factor analyses of data for the three largest ethnic groups (European American, African American, Mexican American) yielded a two factor structure that corresponded to two theoretical approaches to ethnic identity, as hypothesized Similar patterns in magnitude of loadings were observed across groups, indicating that the MEIM could be used as a global composite index of ethnic identify. Ethnic identity was related positively to measures of psychological well-being such as coping ability, mastery, self-esteem and optimism, and negatively to measures of loneliness and depression. MEIM scores also were moderately strong and positive with salience (the importance of a person's own ethnic background in his other life), across ethnic groups.