Coursebooks are essential to language learning and teaching and have a significant influence on the content taught and the learning activities that take place in the classroom. Teachers frequently refer to textbooks while planning their lessons and choosing the exercises they believe will be engaging for students. It is therefore essential to implement Education for Sustainable Development (ESD) in language coursebooks to incorporate it into language instruction. This study investigates how sustainability content is currently presented in various German coursebooks aimed at learners of German at the A1–B2 level on the CEFR scale, aged 15–17 years. The coursebooks used in the analysis were from the UK, Denmark, Finland, the Netherlands, and Norway, and the data were analysed using qualitative content analysis and NVivo software. The framework for the content analysis was based on UNESCO’s Earth Charter and the Roadmap for Implementing the Global Action Programme on ESD, as well as recent research on the role of ESD in language teaching and textbooks. Based on the insights gained from this study, we discuss how to increase the promotion of ESD in language coursebooks and suggest how teachers can facilitate discussions about sustainability-related content in language lessons.