Early school leaving is a major social problem and a socio-political priority in knowledge-based societies, especially in southern European countries that have a tendency for comparatively high dropout rates. The literature has focused strongly on the exogenous factors that cause students to leave school early. Meanwhile, endogenous factors, such as scholastic performance, educational attainment or the holistic needs of students are also important to consider. Early school leaving represents the culmination of a process of disengagement; this article analyses some of the endogenous factors behind it. To this end, we compare early school leaving with educational results from previous stages. We focus on regional and gender inequalities in Spain, where early school leaving rates are the highest in the European Union. The results confirm the correlation between weak scholastic performance and early school leaving. They also reveal that regional and gender imbalances persist.