This article assesses Van Parijs's proposal for an unconditional universal basic income according to the Rawlsian criterion of stability—a criterion Van Parijs arguably shares. First, I examine a number of stability-generating features of conceptions of justice that pertain to their scope and content. Second, I evaluate these features relative to an unconditional versus a conditional scheme, and argue that they favour the latter. Third, I rebut four central objections to the core argument. Although the unconditional scheme may emerge as the winner, all things considered, introducing the factor of stability or sustainability nevertheless deepens our understanding of the nature and justifiability of the basic income proposal.