In this chapter, the concept of powerful knowledge is studied by using the concept of transformation as a key concept to describe the different characteristics of powerful knowledge in educational content relating to education for sustainable development (ESD) . The concept of transformation takes the didactization of disciplinary subject area knowledge into consideration, that is, how it is transformed into something that is teachable in lower secondary school cross-curricular settings (Gericke et al. 2018) . This empirical study focuses on how the concept of powerful knowledge can be understood and characterized in the context of teachers’ discussions from three different subject areas when addressing the same thematic topic of sustainable development (SD) . As the content of SD draws from multiple disciplines addressing the environment, society and the economy, powerful knowledge covering this topic thus needs to be drawn from different disciplines. Based on teachers’ descriptions...