Which conceptions of solidarity will help subjugated, oppressed groups pose liberatory challenges to the regimes under which they suffer? Activists and scholars concerned with liberation err by constraining solidarity to the parameters outlined in conventional moral and political theory and, therefore, by imagining solidarity as dependent on models of identity and shared interests. Organized movements may aim for expanded access to institutional claims and for cultural representation, and yet liberatory movements also have more specific objectives: to challenge the legitimacy of oppressive political and moral regimes, and to put those regimes in the obediential service of the vulnerable and oppressed. I critique notions of solidarity conceived in political philosophy as shared interests, and as a functions of identity in discourses about anti-racist, feminist, and pro-indigenous movements for social justice and cultural inclusion. Using the works of Enrique Dussel, Karl Marx, Friedrich Engels, and Elaine Scarry, I argue that a notion of solidarity developed as a relational concept, primarily as a reference to the laborious activities of relating, can serve as a resource for liberatory projects once we describe the three main ideas as a coherent proposition: liberatory solidarity as relational. The concept refers to when individuals and groups continue to relate, to make one another, for the purposes of liberation despite countervailing exploitative power relations, incentives, and disincentives. Those seeking emancipatory change either labor to relate for the sake of liberation, or preserve the bigger-picture status quo in which disparate and episodic enclave movements rise and fall on the terms set by identity politics and fictive individualistic autonomy.