This study examined the relationship between children's sports participation and emotional well-being including self-reported emotional and behavioral problems and multidimensional aspects of self-concept. Data were collected from 203 young adolescents using a multitrait-multimethod assessment methodology. Information was obtained using a sports questionnaire concerning participation in and perceptions of sporting activities. Emotional well-being was assessed by the Youth Self-Report (Achenbach, 1991) and the Self-Perception Profile for Children (Harter, 1985). The study found that increased levels of sports participation had a positive relationship with aspects of emotional and behavioral well-being, particularly self-concepts. Results also showed that children with increased perceptions of sport-related competencies reported significantly fewer emotional and behavioral problems than did children who were, by external standards (e.g., teacher rating, number of sporting achievements), actually competent at sport. The study also found particular areas of sports participation to be positively associated with self-concept. Evidence suggests a similar beneficial association with some aspects of behavior problems. Practical implications of the findings are discussed along with recommendations for future research.