Studies of nuclear proliferation tend to focus on the fateful decisions to acquire these deadly weapons and the motivations behind their acquisition. In this important contribution, Narang asks a different question. How do potential proliferators go about pursuing a nuclear option, and under what conditions do they succeed? He identifies four different strategies. The early nuclear weapons states were the big powers that had the resources to build the weapons on their own and so could “sprint” to the nuclear finishing line. The hedgers, by contrast, moved more cautiously in developing a nuclear option, not necessarily overtly pursuing it. Examples of this group include U.S. allies such as Japan and South Korea, which for now do not want to jeopardize their relations with Washington by getting the bomb. There are potentially many countries in this category, especially in the Middle East, owing to concern about Iran’s nuclear program. Others, such as Israel and North Korea, were able to get the bomb because allies sheltered them from the full risks of their pursuit of the weapon. The last group consists of countries that tried in secret to acquire or develop nuclear weapons in the hope that they wouldn’t get caught. But that path can be very tricky, as Iran, Libya, and Syria have discovered, and can lead to trouble.