The reasons for the recent and simultaneous appearance, or rise in influence, in much of the world of “fundamentalist” or doctrinally and socially conservative religiopolitical mass movements have been analyzed for individual groups but rarely in a way that compares all the main religions and the regions in which they are strong. Most comparative volumes on fundamentalism are collections, with most authors discussing one area. Exceptions are Mark Juergensmeyer, The New Cold War? Religious Nationalism Confronts the Secular State (Berkeley: University of California Press, 1993) and Bruce B. Lawrence, Defenders of God: The Fundamentalist Revolt against the Modern Age (San Francisco: Harper and Row, 1989). Useful collections include the five volumes of the Fundamentalism Project of the American Academy of Arts and Sciences, edited by Martin E. Marty and R. Scott Appleby and published by the University of Chicago Press (Chicago, 1991–95; full reference in note 3); Richard T. Antoun and Mary Elaine Hegland, eds. Religious Resurgence: Contemporary Cases in Islam, Christianity, and Judaism (Syracuse: Syracuse University Press, 1987); Lionel Caplan, ed., Studies in Religious Fundamentalism (Albany, SUNY Press, 1987); John Stratton Hawley, ed., Fundamentalism and Gender (New York: Oxford University Press, 1994); and Contention, 4:2, 3, and 5:3 (1995, 1996), sections on comparative fundamentalism. Rarer still have been analyses of why such movements have expanded in most areas only since the 1970s, what causes exist in areas where these movements are strong and why they differ from those regions where they are weak or nonexistent, and what, aside from religion, produces different types of movements. Here we will try to see if there are common factors in time and in space that help explain these movements and will look for causes of their similarities and differences. Explanations presented here will stress differences between religious nationalism (or communalism) directed primarily against other religious communities and conservative religious politics directed primarily against internal enemies. Differences between types and levels of preexisting religious beliefs will be examined to suggest why some areas have such movements and others do not. World-wide factors that help to account for the recent rise of religious politics will also be explored.