The Earth Liberation Front (ELF), also known as "Elves" or "The Elves" is the collective name for anonymous and autonomous individuals or covert cells who, according to the ELF Press Office, use "economic sabotage and guerrilla warfare to stop the exploitation and destruction of the environment". The intellectual underpinnings rationalizing such actions is known as Rewilding. The ELF was founded in Brighton in the United Kingdom in 1992 and spread to the rest of Europe by 1994. It is now an international movement with reported attacks in 17 countries and is widely regarded as the Animal Liberation Front's 'younger sister,' because of the relationship and cooperation between the two movements. Using the same leaderless resistance model, as well as similar guidelines to the ALF, sympathizers say that it is an eco-defence group dedicated to taking the profit motive out of environmental destruction by causing economic damage to businesses through the use of direct action

ELF "monkeywrenching" is carried out against facilities and companies involved in logging, genetic engineering, GMO crops, deforestation, SUV sales, urban sprawl, rural cluster and developments with larger homes, energy production and distribution, and a wide variety of other activities, all charged by the ELF with exploiting the Earth, its environment and inhabitants. The Earth Liberation Front has no formal leadership, hierarchy, membership or official spokesperson and is entirely decentralized; instead consisting of individuals or cells who choose the term as a banner to use. Individuals are commonly known to work in affinity groups, known as cells, and are usually self-funded.

Techniques involve destruction of property, by either using tools to disable or the use of arson to destroy, what activists believe is being used to injure animals, people or the environment. These actions are sometimes called ecotage and there are marked differences between their actions in the United States and the United Kingdom.

Jeff "Free" Luers, who is serving a ten year sentence for the firebombing of SUV's at a dealership, which was revised from twenty-two years and ten months, describes why the ELF exists and why they have kept by the guidelines that were initially published for the movement:

With many different reasons why ELF activists carry out economic sabotage, a communique to the press claiming the responsibility for an arson against urban sprawl in December 2000, described the reason a cell the took an action. As Elves usually do, they claimed that burning down the house was non-violent, because it was searched for any living creatures; an issue which is much debated within the environmental movement.^[19]

Any direct action to halt the destruction of the environment and adhering to the strict non-violent guidelines, can be considered an ELF action. Economic sabotage and property destruction are the primary focus of the published guidelines:

• To inflict maximum economic damage on those profiting from the destruction and exploitation of the environment (biophysical).
• To reveal to, and to educate the public about the atrocities committed against the earth and all species that populate it.
• To take all necessary precautions against harming any animal - human and non-human.

Some of the most common and notable attacks are against the development of multi-million dollar houses, known as McMansions, a frequent target in the ELF campaign. In a communique to the ELF Press Officer in North America, that was later published in The Environmental Magazine, the group declared in 2001:

1998/1999

The ELF gained national attention for a series of actions which earned them the label of eco-terrorists, and one of the top domestic terror threats in the United States. This came after the burning of a ski resort in Vail, Colorado, on October 19, costing $12 million. In a communique to the press, the ELF said:

Actions also included sabotaging power lines, the burning of an SUV dealership and the burning down of a logging headquarters causing $1 million in damages. The Elves wrote to the local paper "Let this be a lesson to all greedy multinational corporations who don't respect their ecosystems," with most actions taking place in Oregon. The defendants in the case were later charged in the FBI's "Operation Backfire", which included 17 acts of property destruction.

The ELF then set fire to the Michigan State University on New Years Eve, using a gasoline bomb to cause $1.1 million in damages, because of their GMO-engineering. The next day, commercial logging equipment was set on fire, with "ELF" and "Go Log in Hell" spraypainted on a truck. In March 2008, four activists were charged for both the arsons. On November 27, in Oregon, the ELF burned the Legend Ridge mansion and sent a message to the Boulder Weekly saying "Viva la revolution!" Damages were estimated at $2.5 million.

2000

In March, a total of thirty SUVs were torched, belonging to Joe Romania's dealership, in Oregon, with damages estimated at $1 million. The action was claimed in support of Jeff "Free" Luers, who targeted the very same dealership and was in court for the charges at the time. He was then sentenced to twenty-two years in jail, later revised to ten.

2001

On May 21, a fire destroyed laboratories, offices and archives at the Center for Urban Horticulture, University of Washington, causing a total of $7 million in damages. The arson destroyed 20 years of research and plant and book collections. The ELF claimed responsibility based upon the incorrect belief that the University was involved in genetic engineering of poplar trees ^[48]. No genetic engineering was being conducted. In the wake of the attack, an FBI spokeswoman in Portland, Oregon said "I don't think there's any doubt the ELF is upping the ante".

On November 21, ELF member Ian Wallace planted incendiary devices outside of two buildings on the campus of Michigan Technological University in Houghton, Michigan during the early morning hours. The devices failed, and on March 21, 2009, Wallace was sentenced to three years in prison for the incident by Judge Robert Holmes Bell, who said Wallace "didn't intend to hurt anybody, (but) this is a serious offense." Said Wallace after his conviction, "I have been consumed by shame for what I have done," Wallace said. "My greatest blessing is that no one got hurt."

2003

On August 1, a 206-unit condominium in San Diego was destroyed, with a banner left at the scene saying "If you build it, we will burn it", signed "The E.L.F.s are mad". The damages totaled $50 million after flames reached an estimated 200 feet (61 m) in the air, as over a hundred fire fighters attempted to put out the fire. The destruction was the movements most financially damaging action against a target, with a local preservation group calling the action pointless, noting that "You can go and burn something down, but it's just going to get built again." Exactly three weeks later, 125 SUVs and hummers were torched, costing a total of $3.5 million, with "I love pollution" spray-painted at the scene, and a month later homes being built in San Diego were targeted again, this time costing an estimated $450,000 in damages.

2005

The FBI's most recent report stated that there had been over 1,200 "criminal incidents", within January 2006. A nearly completed 9,600-square-foot (890 m²) house, worth $3 million, was burnt to the ground in Washington. The Herald Net reported that a bedsheet was drapped across the front gate, with a threatening message spray-painted on it.

2008

One of the latest ELF arsons was reported on the morning of March 3, when explosive devices set fire to four multi-million dollar homes from the 2007 Seattle Street of Dreams in Echo Lake, Washington, costing $7 million in damage. Authorities described the act as "domestic terrorism" after finding "ELF" spray-painted in red letters, mocking claims that the homes were environmentally friendly: "Built Green? Nope black! McMansions in RCDs r not green. ELF." A criminology professor replied saying: "The real unfortunate thing is many citizens will empathize with ELF because their goal is the environment."

2009

On March 23 the ELF claim the burning of an excavator in Guadalajara, Jalisco, Mexico State. In one of many recent anonymous communiques, the ELF reported to Bite Back; "Maybe we have not collapsed the system of domination with these actions, but it begins with actions like these."

On September 4 ELF claimed responsibility for using a stolen excavator to overturn two AM radio towers belonging to station KRKO near Seattle, Washington; they claimed that radio waves are dangerous.

A Texas man was arrested after construction workers found a disabled construction vehicle grafiteed with the words "ANOTHER TRACTOR DECOMMISSIONED BY THE E.L.F."