[Call for action: the health sector as a driver of societal transition towards Planetary Health].

Humanity is facing existential challenges that require urgent action to address the triple planetary crises. Drawing on the principles of planetary health, the paper argues that health professionals and the health sector have historically been important drivers of societal change, and that time has come once again for the sector to take up such active roles in addressing the planetary-health challenges. The paper provides an overview of the current frontlines of planetary health in the Netherlands: in education, research, new governance and sustainable leadership, as well as in various movements for greater transformative connection and transdisciplinary collaboration.