INTRODUCTION: Despite the health benefits, a large proportion of girls and boys in Europe do not travel to school actively. A better understanding of the correlates associated with this behavior could guide interventions. This study examines perceived social and environmental correlates of active travel to school (ACTS) from the 2017/18 Health Behavior in School-Aged Children (HBSC) survey in four European countries, with a special emphasis on gender differences (n = …