Before the attacks on the World Trade Center and the Pentagon on September 11, 2001, extremism was a real but remote concern for most Americans. However horrifying, the Oklahoma City bombing in April 1995 -- the other nationally traumatic act of terror in recent memory -- did not lastingly interrupt or change the daily lives of those not directly affected. That bombing, which killed 168 people, brought into view a landscape of heavily armed, fanatically anti-government super-"patriots" and neo-Nazis: disaffected loners crisscrossing the gun show circuit and camouflaged paramilitaries training secretly in the woods. These new militants seemed angrier and more volatile than the fringe figures of the past, bent on attacking America in order to save it -- no matter how great the "collateral damage."

But while Oklahoma City sounded a warning about the possibly catastrophic consequences of homegrown rage, for most the threat of the homegrown radicals was a distant reality. Moreover, the militia movement subsequently seemed to fade from view, weakened perhaps by prosperous times and certainly by organizational incompetence, infighting, the nonappearance of the New World Order and a general lack of ardor.

By contrast, the man convicted of murdering 168 people in Oklahoma was grimly resolved to strike at his perceived enemies. Timothy McVeigh (executed on June 11, 2001) left an unnerving impression in part because he did not fit the far-right stereotype: the coarse, bellicose, race-hating workingman. McVeigh's family was middle class; he was articulate and polite, not driven by bigotry, never ranting; to observers of the right-wing, even his belief in the evils of federal government was unexceptional. His anonymously American quality made him seem incommensurate with the pain and damage he caused (leading to extensive theorizing about conspiracies behind the bombing).

But even as his biographies implied that McVeigh represented, in some fashion, a ghastly underside of the American dream (titles included American Terrorist, All-American Monster, One of Ours), his most notable quality -- his terse, military, inhuman single-mindedness --proved ultimately comforting (even though repellent). For McVeigh was unique: it became clear to most Americans after the bombing that the intensity of his convictions and his willingness to sacrifice himself were by no means characteristic of a broader movement. His acknowledged guilt and his claim to virtually all the responsibility for the crime helped reinforce the profound assumption that life in America is essentially free from terror. (McVeigh became so identified with Oklahoma City that his few confederates either faded into oblivion, as with Michael Fortier, with whom he discussed his plans and who testified against him, or came to be seen as merely nominal, as with co-conspirator Terry Nichols.) In the end, McVeigh's concerns were not merely personal and could not be discounted, but he proved neither the poster boy for a revolution from the fringe nor a gauge of broader disaffection.

Nor have other outbreaks of extremist violence in America, though tragic, threatened the country's general sense of well-being. Anti-abortion radicals have committed several murders and many bombings and harassments. These crimes may have intimidated women seeking abortions, but, with few exceptions, anti-abortionists specifically threaten only those who work at clinics, a tiny fraction of the population. Various terrorist groups have crossed into public consciousness -- The Ku Klux Klan, The Weather Underground, The Order, FALN (Armed Forces of National Liberation, a violent Puerto Rican nationalist group) and many others -- but most of these targeted discrete groups (particular ethnicities, law enforcement, government) or were active only for short periods or in certain sections of the country.

With the mass deaths and massive destruction of September 11, and facing the possibility of even greater dangers, Americans abruptly found that extremist terror was no longer a brief incursion into their lives. Within a day it had forced itself into their routines and into the way they viewed their nation and the world. More thoroughly than at any time since the Second World War, we have been forced in this country to consider the constitutional liberties we have inherited, and consciously to help safeguard them. It is too facile to label the events of September 11 as merely an attack on American democratic values, but there is no question that America's exceptionally free society acts as a kind of reverse aphrodisiac, galvanizing and attracting all manner of hatreds and embodying the greatest evil. More than that, it offers a home to those who hate it, and thereby requires exquisite calibrations of freedom and vigilance, and the creative negotiation of ideological differences, to exist.

This second edition of Extremism in America is being published during this period of extraordinary change and challenge. Not all of the figures, groups and movements discussed in these pages concur with the American neo-Nazi who said of the September 11 terrorists, "we may not want them marrying our daughters...but anyone willing to drive a plane into a building to kill Jews is alright by me. I wish our members had half as much testicular fortitude." Many here do share these sentiments, however; some have acted or threaten to act on them; and all join with foreign terrorists in despising the ethos of equality and pluralism, and the impermeability of the rule of law, that defines American life.

Moreover, while current discussions of extremism have focused on Islamic terrorism, the heightened attention to public threats has increased interest in and scrutiny of domestic terror as well. In a new way, we have seen that expressions of hate inspire violence and that violence on a vast scale can occur in this country. We have reached an especially opportune moment to identify and measure the scope of extremist activity, and the Anti-Defamation League hopes that Extremism in America will be an important tool in that effort.

This volume is designed to be the cornerstone of a broad encyclopedia of extremism. It is a living document: new chapters and updates will be regularly added to ADL's law enforcement Web site (www.adl.com/LEARN) and periodically released in print. The guide includes 35 entries about the prominent players and trends in the extremist world, including a comprehensive listing of white power music groups and an index of the most prominent symbols used by hate groups. We have also appended an annotated bibliography for further study.

The landscape of American extremism constantly changes. Recent years have witnessed:

• increasing emphasis on "lone wolf" activism (acting in small cells or alone to avoid getting caught);

• the ascendancy of the Internet as an instrument for extremist organizing and disseminating information;

• the use of white power music as a recruiting tool by professional bigots like National Alliance head, William Pierce;

• the emergence of Holocaust denial as an extremist lingua franca, both domestically and worldwide as well as budding alliances between Western deniers and their Middle Eastern counterparts -- even as David Irving lost a widely publicized libel lawsuit and other deniers were repeatedly defeated in their courtroom battles;

• the increasing role of women in far-right movements;

• the apparent demise of neo-Nazi stronghold Aryan Nations after the group and its aging leader, Richard Butler, lost a multimillion dollar civil decision (stemming from an assault by its security guards);

• opportunistic support of the antiglobalization movement and of the Palestinian cause by some on the far right;

• the convergence between the radical right and some elements of the radical left -- conspiratorial antiglobalists and hard-core anarchists in particular;

• and, most recently, support for foreign anti-American terrorists.

These pages treat all of these issues, and many more, in the belief that information is an invaluable asset in promoting a more civil and secure society.