This paper examines how economic development affects interstate conflict. We hypothesize a non-linear relationship between development and interstate conflict, where extreme poverty and prosperity reduce the risk of militarized conflict. This occurs because states at an intermediate level of development have both the opportunity and willingness to pursue territorial claims, which makes them prone to militarized interstate conflicts. Our empirical analyses confirm this non-linear relationship. Developed states, more reliant on services and international commerce and less on natural resources for their economic growth, are less likely to push territorial claims, decreasing their involvement in interstate conflict. High development also mitigates the combined effects of population growth and military power that serve to increase the risk of interstate violence. Additionally, we show that population growth, but not population density, contributes to the occurrence of militarized disputes.