Aim: To explore the relationship between habitual physical activity and psychological well-being in children. Methods: Seventy children (35 boys, 35 girls), age 10.4 ±0.4 y, wore hip pedometers over a period of 7 d. Well-being was conceptualized as the presence of global self-esteem and the absence of anxiety and depression and assessed with the use of three questionnaires. Results: Correlation analyses revealed that habitual physical activity had a strong association with global self-esteem (r = 0.66), depression (r =-0.60) and anxiety (r =-0.48). However, using partial correlations, the significant relationships were removed for anxiety and depression, but remained for self-esteem (r = 0.36). When groups were created based upon activity level, children achieving > 12 000 stepsday had more positive psychological profiles than children achieving < 9200 stepsday. Conclusion: The results support the findings from previous studies that have explored the relationship between physical activity and well-being, but represent the first to use a mechanical measure of physical activity over a 7-d period to assess the relationships. The actual step counts associated with more positive psychological well-being can be shown to be in line with the recommended guidelines that children accumulate a minimum of 60 min of moderate-intensity activity per day. Aim: To explore the relationship between habitual physical activity and psychological well-being in children. Methods: Seventy children (35 boys, 35 girls), age 10.4 ± 0.4 y, wore hip pedometers over a period of 7 d. Well-being was conceptualized as the presence of global self-esteem and the absence of anxiety and depression and assessed with the use of three questionnaires. Results: Correlation analysis revealed that habitual physical activity had a strong association with global self-esteem (r = 0.66), depression (r = -0.60) and anxiety (r = -0.48). However, using partial correlations, the significant relationships were removed for anxiety and depression, but remained for self-esteem (r = 0.36). When groups were created based upon activity level, children achieving> 12 000 stepsday had more positive psychological profiles than children achieving <9200 stepsday. Conclusion: The results support the findings from previous studies that have explored the relationship between physical acti vity and well-being, but for the first to use a mechanical measure of physical activity over a 7-d period to assess the relationships. The actual step counts associated with more positive psychological well-being can be shown to be in line with the recommended guidelines that children accumulate a minimum of 60 min of moderate-intensity activity per day.