For public opinion to have an effect on foreign policy, it must first enter into the political debate over policy. I classify issues according to how they are presented to the public, the key variables being crisis/non-crisis, the level of media salience, and whether elites agree or disagree on policy. These three variables determine issue structure, which in turn affects the extent to which public opinion is injected into the debate on that issue.^ Specific hypotheses are derived from the issue structure typology. The rally effect of crises is modified by whether or not elites are in agreement on how to meet the crisis. Indeed, the character of elite debate is very important in determining the role of public opinion in non-crisis situations as well. Elites, especially when they disagree on a salient issue, indicate their responsiveness to public opinion by tailoring their rhetoric to match established opinion dikes within mass sentiment. Public knowledge is more likely to increase on salient issues that divide elites.^ I present an initial test of the issue structure typology by using it to analyze four cases of the Reagan Doctrine. Relying on surveys of public opinion as well as on a content analysis of New York Times stories, I apply the typology to funding rebel groups in Afghanistan, Angola, and Nicaragua, as well as to the invasion of Grenada. The issue structure typology proves very useful, but a complete test requires considerably more data than is routinely available.