This article examines the affordances and limitations of textbooks for promoting action competence for sustainable development. Based on a content analysis of Swedish lower secondary level textbooks in geography and biology, we investigated how content about sustainable development is organised and formulated, the ways its multidimensional character is described, and how conflicts relating to achieving sustainability are addressed. We found that for both subjects, textbooks provided a fair amount of content about sustainable development, but that relations between its ecological, economic and social dimensions and between different subjects are routinely underdeveloped. We also found that the content about sustainable development obscures complexities and conflicts that are crucial for understanding the challenges involved with achieving sustainability, and taking action. In conclusion, we argue that such textbooks substantially limit the potential for promoting action competence for sustainable development, i.e. through cross-curricular approaches and critically assessing problem-oriented actions at collective and individual levels.