How does political accountability in democracies affect leaders’ incentives for international cooperation? We consider how term limits should affect international environmental agreement (IEA) participation. Pursuing environmental protection as a public good coincides with the political survival incentives of democratic leaders. Term limits decouple leaders’ policy priorities from their political survival incentives, discouraging IEA participation. However, prioritization of environmental concerns increases with economic development. As such, the effect of term limits on IEA participation should be strongest in rich democracies. We test these arguments using data from the International Environmental Agreements Database from 1970 to 2011. Democratic leaders, particularly in rich democracies, sign fewer IEAs when freed from the reelection motive. We also consider the potential that term limits could favor IEA participation if doing so aligns with a leader's preferences. This potential should be greatest in poor democracies where citizens place less emphasis on environmental protection, though we find little evidence for this expectation. The findings have important implications for understanding the determinants of IEA participation and the political accountability–international cooperation relationship. Whereas some argue that electoral incentives that cause leaders to favor present over future concerns undermine environmental cooperation, our results suggest that political accountability in democracies can promote treaty participation.