Our economic rules are generally based on the notion that self-interest and competition are natural human impulses, with conservatives suggesting that markets will channel those forces into equilibrium and others arguing to constrain individual and business action with appropriate state intervention. But humans are not just self-interested; we all have a desire to belong and connect in community. What would it mean to build a new solidarity economics? How would such a new economic theory and narrative play out in terms of organizing and change, norms and practices, politics and policy? How could we build such an economy at scale—and what does it mean for our contemporary crises of inequality, separation, and fragmentation?