This paper examines the classification of terrorism articles in two newspaper indexes, the New York Times Index and the London Times Index, and two periodical indexes, the Reader's Guide to Periodical Literature and the British Humanities Index, from 1966 to 1985. The indexes are compared in several ways: by the year in which the category terrorism first appeared; by the changing nature and number of headings and related headings; by the changing number of articles under each heading; and by the different tactics, regions, targets, and other themes emphasized in these articles for each year. The changing patterns in these quantitative and qualitative parameters over the 20-year period are analyzed in terms of regional differences (United States versus United Kingdom) and index differences (newspapers versus periodicals). The results are also compared with other research on media and terrorism that shows that images of terrorism in the media do not represent an accurate picture of the nature and extent of terrorism in the real world.