The most serious problem facing the United States, according to many scientific and political leaders, is the threat of nuclear war. Yet the standard survey question on the most important problem facing the country has often shown little public concurrence with this assumption. Our article uses experimentation in national samples to test whether this difference can be traced to limitations in either the form or the wording of the standard question. The results indicate that there are some important systematic differences between open and closed versions of the question, and also differences that result from reference to the nation as distinct from the world, but neither type of difference accounts for the infrequent mention of nuclear war on the standard question. Instead, other evidence indicates that most Americans believe that nuclear war is not going to happen at all, or that if it does happen it will be too far in the distant future to be of pressing concern to them personally.