There is an old saw in political science that difficult conditions become problems only when people come to see them as amenable to human action. Until then, difficulties remain embedded in the realm of nature, accident, and fate -a realm where there is no choice about what happens to us. The conversion of difficulties into problems is said to be the sine qua non of political rebellion, legal disputes, interest-group mobilization, and of moving policy problems onto the public agenda.' This article is about how situations come to be seen as caused by human actions and amenable to human intervention. Despite the acknowledged importance of this phenomenon as a precursor to political participation and to agenda setting, there is little systematic inquiry about it in the political science literature. For the most part, the question is dealt with under the rubric of agenda setting, even though the transformation of difficulties into problems takes place in something of a black box prior to agenda formation. Three strands of thinking in the agenda literature contribute indirectly to an understanding of this topic. One strand focuses on the identity and characteristics of political actors -leaders, interest groups, professionals, breaucrats. It looks at the actors' attitudes, resources, and opportunities