This study examined the relationships between established socio-motivational factors and children's physical activity levels daily and during physical education classes. A total of 307 middle school students (149 boys, 158 girls) from a suburban public school in the Southern United States participated in this study. Participants completed standardized questionnaires measuring their socio-motivational factors in the first week of data collection. Their physical activity levels in physical education class and 1-week physical activity levels were assessed in the following two weeks. Results revealed that 1) children's general physical activity enjoyment had predictive strength to their physical activity levels in physical education class, and 2) children's physical activity self-efficacy, perceived friend support and physical activity enjoyment were significant predictors of their daily physical activity levels. (Contains 3 tables.)