The aims of this 2005 study from Portugal were: 1) to observe participation in moderate-to-vigorous PA during school recess periods; 2) to determine the relative importance of PA during recesses to overall daily PA; and 3) to examine differences in PA between the sexes during unstructured recess periods. Only 10 boys and 12 girls aged 8-10 years participated. The results of this study suggest that school recess time is an important setting to promote moderate-to-vigorous PA and contributes to daily PA in young children, especially in girls.