The objectives were to examine the factorial structure of the Academic Procrastination Scale-Short Form (APS-S) and the measurement invariance across gender and educational levels, to determine possible differences in procrastination across gender, educational levels, and grades. The sample was formed of 1486 Spanish primary and secondary school students between the ages of 7 and 19 years. A one-factor model provided an adequate fit. Scalar and partial scalar invariance were achieved through gender and educational levels, respectively. Internal consistency was good and slightly higher for secondary school students than primary school students. Moderate convergent validity was obtained. The APS-S scores showed a weak but significant correlation with math anxiety. Procrastination scores increased with grade, and males showed significantly higher procrastination scores than females. The Spanish APS-S demonstrated adequate reliability and validity scores and could be a useful tool for examining academic procrastination in children and adolescents.