Do world politics affect the adoption of new technology? States overwhelmingly rely on technology invented abroad, and their differential intensity of technology use accounts for many of their differences in economic development. Much of the literature on technology adoption focuses on domestic conditions. The authors argue instead that the structure of the international system is critical because it affects the level of competition among states, which in turn affects leaders’ willingness to enact policies that speed technology adoption. Countries adopt new technology as they seek to avoid being vulnerable to attack or coercion by other countries. By systematically examining states’ adoption of technology over the past two hundred years, the authors find that countries adopt new technologies faster when the international system is less concentrated, that changes in systemic concentration have a temporally causal effect on technology adoption, and that government policies to promote technology adoption are related to concerns about rising international competition. A competitive international system is an important incentive for technological change and may underlie global technology waves.