The stagnation of academic results in Chilean education drove the center-left government of President Michelle Bachelet (2014-2018) to propose a reform focused on classroom instruction. Thus, a new teacher professional development system was proposed with the aim of significantly improving the quality of instruction. This article describes the characteristics of this reform, followed by a description of the political challenges it faced for its processing and final approval before being made into a law, concluding with a discussion of the lessons learned from this experience in terms of systemic education changes. Among these lessons, it´s necessary to consider the need to progressively collect evidence to mobilize decision makers towards the desired reform; the need to find systematic solutions to complex education issues; the difficulty in regulating actors and processes that depend on market forces when these have already been settled in a large scale in the education system; and the importance of an effective communication, dialogue and negotiation with the education stakeholders who embody these reforms, especially those who have difficulty with governance and representation.