This is a new initiative to address the impact of a changing planet on mental health. The goal is to build an inclusive and actionable research agenda and a connected, supported and engaged community of practice with the right tools to enact that agenda. The Planetary Health Alliance leads efforts in North America and Europe by building the regional community, shaping the agenda through dialogue, supporting capacity building in research and advocacy, generating new knowledge, and identifying opportunities to ensure the long-term sustainability of the regional community. (More on planetaryhealthalliance.org )