The aim of this study was to examine modifiable biological, psychological, behavioral and social-environmental correlates of physical activity among 1129 Norwegian 11-year-old children within a cross-sectional sample from the HEalth In Adolescents study. Physical activity was assessed by accelerometer, and weight and height were measured objectively. Age- and gender-specific cut-off points proposed by the International Obesity Task Force were used to define body mass index. Social-environmental variables were self-reported by questionnaire. Hierarchical regression (linear mixed models) revealed that normal weight children scored higher on percentage daily moderate-to-vigorous physical activity [% daily moderate to vigorous physical activity (MVPA)] than overweight/obese children (P