Schools present a privileged environment to address physical inactivity. Actions to promote an active lifestyle have been launched for over 20 years in the European Union. In French-speaking Belgium, such actions have multiplied, but efficiency remains undocumented due to the lack of systematic data regarding health and physical activity (PA) promotion at school. This research aimed to create a tool and to use it to establish an empirical baseline regarding PA promotion in secondary schools. Six main dimensions, all broken into variables, were identified after an extensive literature search. Six experts assigned different weighting factors to each dimension and variable, thereby allowing the attribution of scores. Fifty-one secondary schools were analyzed on this basis. The mean global score of the sample was 44.7 on a maximum of 100. PA was better promoted in urban schools with 250 to 499 students with high socioeconomic status. Real in-school policies aimed at promoting PA were lacking. Active transport to and from school was seldom encouraged. The number of PE classes was insufficient. The facilities used were of better quality than expected. This exploratory research constitutes an important step toward the conception of a tool based solely on objective variables. It should also serve as a catalyst to implement new field projects