The right-wing extremist groups thrive on cultural xenophobia (fear of anything foreign or unfamiliar), which has varied in scope and intensity over the period studied. Currently, the Klan, the Aryan Nations, and groups sharing similar views are in decline and disarray, competing for an ever shrinking supply of those vulnerable to their appeals. Federal prosecution and State laws banning paramilitary activities and punishing racial and religious harassment have contributed to this decline. Law enforcement in this area, however, is inconsistent, and history suggests that right-wing extremist organizations pass through dormant periods and then have a resurgence when conditions are suitable for an audience receptive to their message. International conflicts and the flood of immigration from Third World regions will continue to generate cultural xenophobia. Changing population patterns or abrupt shifts in the economy magnify class differences and stimulate debates about racial and ethnic issues and cultural values. Current concerns about AIDS, drugs, and criminal violence show no signs of diminishing. Current extremist groups are better armed than their predecessors, and they are skilled in the use of mass communication techniques. 64 footnotes.