After almost 20 years of environmental impact assessment (EIA) in Chile, in 2010 the country adopted a more strategic view in order to include sustainability objectives in the development of policies and plans: the strategic environmental assessment (SEA). For supporting this new process, the Ministry of Environment developed a series of guidelines delineating the focus and methodology for an adequate implementation of SEA. These guidelines have been widely embraced by different actors as a reference to elaborate the environmental reports. In this opinion letter, we express our view upon the advances and challenges in the development of the SEA process in Chile and the role of evolving guidelines that have shaped the current implementation. The most relevant advances are related to an increasing awareness regarding the integration of sustainability issues in decision-making and the complementarity of SEA with the elaboration of policies and plans. Challenges are still present, and they are mainly related to the practical implementation rather than the availability of guidelines, where SEA is slowly being understood as different from the traditional EIA.