The educational system in Mexico has allowed teachers without preparation and training in leadership to pursue leadership positions. This paper presents the findings of a study aimed at analyzing the processes of leadership learning experienced by school principals in the course of their leadership practice. The methodology used was a qualitative multiple case study using a biographic narrative interpretative method. Findings show that principals experienced challenges throughout their practice and that these role experiences enabled leadership learning and improvement of their leadership practice. Their learning is contextualized and shaped by the practical experiences that are not only unique but they also enable on-the-job leadership learning.