In this article, we discuss principals' perspectives on the priority given to the place in the curriculum of and the supporting practices related to health and sustainability education in schools in Denmark (for pupils aged 6-16). The study is situated within the discourses about critical health and sustainability education and treats the two issues as societal challenges that are important to address in schools as educational examples. We draw on the literature on school leadership challenges linked to global neoliberal trends in educational reform. The context of the study is the ongoing school reform in Denmark. The data were generated through an online survey of principals in Denmark (n = 118). The findings show that although the principals view school as an important arena for health and sustainability education, their actual support for such education lags behind. Health education is prioritized somewhat more than sustainability education; however, both are characterized by insufficient attention to teachers' professional development and the low prioritization of collaboration within the school and between the school and community actors. Acknowledging the contradicting demands that principals face in the context of the reform, we argue for reconnecting the concept of leadership with the wider purposes of schooling and for providing space for an emergent, whole-school curriculum that addresses health and sustainability.