This study examined the measurement and interpretation of self-concept among the growing population of children who are English Language Learners (ELLs). More specifically, a 3-group analysis was conducted comparing native English-speaking children, Spanish-speaking ELLs, and ELLs from Asian language backgrounds. Data were drawn from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 (Pollack, Atkins-Burnett, Rock, & Weiss, 2005), in which an adapted version of the Self-Description Questionnaire-I (SDQ-I; Marsh, 1990b) was used to measure children's self-concept in 3rd grade. Participants were 11,020 native English-speaking children, 1,277 Spanish-speaking ELLs, and 546 ELLs from Asian language backgrounds. Multigroup confirmatory factor analyses showed that the SDQ-I measured self-concept similarly across children from all 3 language groups. Cross-group comparisons of latent means indicated significant differences in academic self-concept, with Spanish-speaking ELLs reporting higher academic self-concept in reading, mathematics, and all school subjects compared to native English-speaking children. Asian language ELLs reported higher academic self-concept than native English-speakers only in the subject of mathematics. Regarding social-emotional self-concept, Spanish-speaking ELLs reported significantly more internalizing and externalizing problems compared to native English-speaking children, whereas Asian language ELLs reported fewer externalizing problems. ELLs from Asian language backgrounds also rated themselves significantly lower on peer relationships. The authors discuss implications for researchers and educators and offer suggestions for future areas of study. (Contains 1 figure and 3 tables.)