The quality of our educational systems depends, among many other factors, on the involvement, autonomy and professional development of teachers. Self-regulation capacity and, specifically, the self-regulation of learning is one of the key factors contributing to the academic and professional development of teachers. The purpose of this study is to delve into the understanding of pre-service and in-service schoolteachers' self-regulated learning processes, as part of their professional competencies' development. Through a qualitative methodology, semi-structured interviews, designed ad-hoc for the study, were conducted with eleven pre-service and twelve in-service schoolteachers. The interviews addressed aspects associated to the planning, the monitoring, and the reflection of their learning processes and professional development. Results show that self-regulated learning is an ability that is learned during their initial training, and which is continuously developed and defined during their professional practice, which shifts from the individual to the collective, and which is regulated through motivation. The study leads us to conclude that without a doubt, the development of self-regulation of learning processes improves and completes the professional practice of teachers. Therefore, it is necessary to incorporate self-regulated learning in the study plans of schoolteacher's training and the school's strategic plan, as a key competency that must to be developed in an intentional, planned, and conscious manner.