"Resistance to Civil Government", also called "On the Duty of Civil Disobedience" or "Civil Disobedience", is an essay by American transcendentalist Henry David Thoreau, first published in 1849. In it, Thoreau argues that individuals should prioritize their conscience over compliance with unjust laws, asserting that passive submission to government authority enables injustice. Thoreau was motivated by his opposition to slavery and the Mexican–American War (1846–1848), which he viewed as morally and politically objectionable.

The essay has had a significant impact on political thought and activism, influencing figures such as Mahatma Gandhi, who adopted its principles in the struggle for Indian independence, and Martin Luther King Jr., who cited it as a key influence during the American civil rights movement. Its themes of individual responsibility and resistance to injustice have made it a foundational text in the philosophy of nonviolent protest and civil disobedience.

In 1848, Thoreau gave lectures at the Concord Lyceum entitled "The Rights and Duties of the Individual in relation to Government". This formed the basis for his essay, which was first published under the title "Resistance to Civil Government" in an 1849 anthology by Elizabeth Peabody called Æsthetic Papers. The latter title distinguished Thoreau's program from that of "non-resistants" or Christian anarchists like Adin Ballou and William Lloyd Garrison, as Thoreau argued that their insistence on nonresistance as praxis against the state was grossly ineffectual. Nonetheless, Thoreau was initially inspired by the Christian anarchist ideals espoused by Ballou and Garrison. Resistance also served as part of Thoreau's metaphor comparing the government to a machine: when the machine was producing injustice, it was the duty of conscientious citizens to be "a counter friction" (i.e., a resistance) "to stop the machine".

In 1866, four years after Thoreau's death, the essay was reprinted in a collection of Thoreau's work (A Yankee in Canada, with Anti-Slavery and Reform Papers) under the title "Civil Disobedience". Today, the essay also appears under the title "On the Duty of Civil Disobedience", perhaps to contrast it with William Paley's "Of the Duty of Civil Obedience" to which Thoreau was in part responding. For instance, the 1960 New American Library Signet Classics edition of Walden included a version with this title. "On Civil Disobedience" is another common title.

The word civil has several definitions. The one that is intended in this case is "relating to citizens and their interrelations with one another or with the state", and so civil disobedience means "disobedience to the state". Sometimes people assume that civil in this case means "observing accepted social forms; polite" which would make civil disobedience something like polite, orderly disobedience. Although this is an acceptable dictionary definition of the word civil, it is not what is intended here. This misinterpretation is one reason the essay is sometimes considered to be an argument for pacifism or for exclusively nonviolent resistance. For instance, Mahatma Gandhi used this interpretation to suggest an equivalence between Thoreau's civil disobedience and his own satyagraha.

The slavery crisis inflamed New England in the 1840s and 1850s. The environment became especially tense after the Fugitive Slave Act of 1850. A lifelong abolitionist, Thoreau delivered an impassioned speech which would later become "Civil Disobedience" in 1848, just months after leaving Walden Pond. The speech dealt with slavery and at the same time excoriated American imperialism, particularly the Mexican–American War.

Thoreau asserts that because governments are typically more harmful than helpful, they therefore cannot be justified. Democracy is no cure for this, as majorities simply by virtue of being majorities do not also gain the virtues of wisdom and justice. The judgment of an individual's conscience is not necessarily inferior to the decisions of a political body or majority, and so "[i]t is not desirable to cultivate a respect for the law, so much as for the right. The only obligation which I have a right to assume is to do at any time what I think right.... Law never made men a whit more just; and, by means of their respect for it, even the well-disposed are daily made the agents of injustice." He adds, "I cannot for an instant recognize as my government [that] which is the slave's government also."

The government, according to Thoreau, is not just a little corrupt or unjust in the course of doing its otherwise-important work, but in fact the government is primarily an agent of corruption and injustice. Because of this, it is "not too soon for honest men to rebel and revolutionize".