Monkeywrenching is a form of sabotage which focuses on creating serious economic damage, thus putting a temporary or permanent halt to activities which the monkeywrencher believes are undesirable. The activity is closely associated with the environmental movement, although other causes have embraced monkeywrenching as well. Different monkeywrenchers are governed by different ethical codes, and a number of guides to monkeywrenching have been published for those who might be seeking inspiration.

The concept of throwing a monkey wrench into a situation to confuse it dates back to the late 1800s. By 1918, the term “throw a wrench in the works” was used specifically in the context of industrial sabotage. Activists who fought for better working conditions and pay might choose to directly damage corporate machinery in the hopes of causing a standstill in factory operations. While the equipment was repaired, the workers could put forth their requests. Workers would also deliberately destroy machinery owned by companies with questionable practices, in the hopes of shutting them down.

In 1975, Edward Abbey's novel The Monkey Wrench Gang was published, and monkeywrenching became forever entwined with environmental activism. The purportedly fictional book documented the adventures of a miscreant crew who were bent on stopping development and expansion in the American West. For many environmental activists, the book became a sort of Bible, romanticizing monkeywrenching and providing practical tips and techniques as well. 10 years later, Dave Forman published Ecodefense, a sort of monkeywrenching manual which advocated ecotage to save the natural environment before it was destroyed.

Acts of monkeywrenching can range from the benign to the potentially very dangerous. A monkeywrenching band may choose to try and permanently incapacitate machinery and equipment, or it may seek to inflict damage which will only require repairs. In the first sense, monkeywrenching is meant to bring development to a halt, while in the second, monkeywrenching buys more time for negotiations and discussions about the issue.

Environmental activists are split on the topic of monkeywrenching. Some embrace it as a valid method of protest, while others believe that it ultimately hurts the environmental movement. Supporters of monkeywrenching may also be split on which types of monkeywrenching are acceptable, with some monkeywrenchers striving to prevent damage to living organisms. Others are less circumspect, and people have been injured or killed as a result of monkeywrenching activities. As a general rule, it is considered polite to warn companies about potentially dangerous forms of monkeywrenching, such as sabotage to heavy equipment which may result in operator injury.