Examined the relationship between level of children's sports participation and emotional well-being including self reported emotional and behavioral problems, self-concept, achievement motivation and participation motivation. Data was collected from 203 Form One and Two students from five schools using a multitrait- multimethod assessment methodology. Information was obtained concerning participation in and perceptions about 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 well-being particularly self-concept. Results also showed children with increased perceptions of sport related competencies reported significantly fewer emotional and behavior problems than children who were, by an external standard (i.e., teacher rating of athletic competence), actually competent at sport. The study replicated and extended research in this area. Caveats are discussed including issues relating to inferring a causal relationship between sports participation and emotional well-being. Future research and methods for studying the psychological effects of sport are recommended.