Portugal, like many nations, has embraced the United Nations’ Sustainable Development Goals (SDGs), recognizing the critical role of education in achieving these objectives. This study delves into Portugal’s actions and plans to promote energy efficiency and sustainability literacy in secondary schools, aligning with SDG targets. Challenges remain in ensuring student engagement, fostering cross-sectoral collaboration, and establishing robust monitoring and evaluation mechanisms. These aspects are crucial for maximizing the impact of education initiatives and aligning with SDG aspirations. A comprehensive analysis of Portugal’s educational policies, plans, and implemented programs was conducted. Additionally, relevant literature and public reports were reviewed to gather insights into the current state of energy efficiency and sustainability education in Portuguese secondary schools. This chapter aims to qualitatively identify the effectiveness and potential gaps in current educational approaches in promoting more sustainable behaviors, literacy on SDG vectors, and awareness of more efficient and conscious energy use. The analysis will also cover academic dynamics and explain its energy footprint related to the education system with decentralized infrastructures. The method of the literature review focuses on obtaining information on the state obligations assumed by Portugal and on the effective actions taken. The findings presented show, through a qualitative analysis, how the challenge is still in its early stages. Some successful strategies that are already emerging as paths to desired effectiveness and educational coverage will be presented.