When security and arms control analysts list what has helped keep nuclear weapons technologies from spreading, energy economics is rarely, if ever, mentioned. Yet, large civilian nuclear energy programs can—and have—brought states quite a way towards developing nuclear weapons; and it has been market economics, more than any other force, that has kept most states from starting or completing these programs. Since the early 1950s, every major government in the Western Hemisphere, Asia, the Middle East, and Europe has been drawn to atomic power’s allure, only to have market realities prevent most of their nuclear investment plans from being fully realized. Adam Smith’s Invisible Hand, then, could well determine just how far civilian nuclear energy expands and how much attention its attendant security risks will receive. Certainly, if nuclear power's economics remain negative, diplomats and policymakers could leverage this point, work to limit legitimate nuclear commerce to what is economically competitive, and so gain a powerful tool to help limit nuclear proliferation. If nuclear power finally breaks from its past and becomes the cheapest of clean technologies in market competitions against its alternatives, though, it is unlikely that diplomats and policymakers will be anywhere near as able or willing to prevent insecure or hostile states from developing nuclear energy programs, even if these programs help them make atomic weapons. Will the global spread of nuclear power programs, which could bring many more countries much closer to acquiring nuclear weapons capabilities, be an inevitable consequence of energy market economics? Or is such an expansion impossible without government subsidies and new policies to support them? This volume showcases the analyses of some of the world's leading energy experts to shed light on this key 21st century security issue.