This article develops a theory of single-party regime consolidation to explain the dramatic variation in longevity among these regimes. The strength of the opposition and rent scarcity during party consolidation, it argues, structure the choices available to elites as they decide how to build a support base. A weak opposition and ready access to rents makes a low-cost consolidation possible, but these conditions provide little incentive to build a robust coalition or strong party organization; this trajectory generates weak single-party rule that is likely to collapse in a crisis. Conversely, elites who face a powerful opposition and scarce rents have no choice but to offer potential allies access to policy-making and have powerful incentives to build a strong and broad-based party organization. Ruling parties that emerge from initial conditions like these prove more resilient during later crises. The author conducts an initial test of the argument against paired comparisons of Guinea-Bissau and Tanzania and of Indonesia and the Philippines.