Most empirical studies on states’ personnel contributions to UN peacekeeping operations (PKOs) use a state’s annual contributions as the unit of analysis. A critical problem of the state-level analysis is that it ignores the fact that states have to decide how to distribute these peacekeepers among more than a dozen peacekeeping missions. Ignoring the mission-level decision misses a significant part of states’ UN PKO contributions and could bias our empirical analysis. We propose a two-level model that sees a state’s UN PKO contributions as the interactions between the state-level and mission-level factors. This model is employed to revisit the heatedly debated “reimbursement hypothesis”. Our analysis of the empirical data between 1990 and 2018 shows a mixed relationship between states’ economic development and their UN PKO contributions. We also find that middle-income rather than low-income countries are the most critical providers of UN PKOs since the end of the cold war.