President Biden has put the idea of deeper democratic cooperation at the centre of his statements on foreign policy. But what exactly this will entail, conceptually and operationally, and how it might overcome the challenges offered by its critics, has remained elusive. In this essay published by The Washington Quarterly, USSC non-resident senior fellow Charles Edel and Hal Brands describe what democratic solidarity would look like in practice, lay out the eight pillars around which such a strategy should revolve, and anticipate the tensions and critiques such a strategy would face.