Responding to the scientific and social complexities of the climate crisis requires bringing all of humanity’s wisdom into the room and working in ways that build bridges across traditional boundaries. Foundation leadership must deploy a new kind of grantmaking that deliberately bridges the usual divides, insists on inclusiveness, seeks untapped resources and reaches new partners, because philanthropy must mobilize resources and leverage impact if it is to stay relevant in today’s rapidly changing climate, both eco-wise and market-wise.