One major point of agreement in the vast literature on national security and foreign policy is that the role of public opinion is marginal compared to political, military and economic factors. Public opinion is often considered a residual category which must be kept in mind, but need not be made the center of attention. Public opinion has played only a minor role in considerations of national security policy research. Academics and politicians alike seem to feel that the role of public opinion in security matters is of relatively minor import, but the pragmatic politicians are much more concerned with the general mood of the moment. The truth of the matter is that policymakers are unlikely to ignore public opinion. The expectation is that public opinion will influence policy, including foreign and defense policy. In considering public opinion as a factor of national security policy, two central issues emerge. The first is an empirical issue, the second a normative one.