Liberation News Service (LNS) was a New Left, anti-war underground press news agency that distributed news bulletins and photographs to hundreds of subscribing underground, alternative and radical newspapers from 1967 to 1981. Considered the "Associated Press" for the underground press, at its zenith the LNS served more than 500 papers. Founded in Washington, D.C., it operated out of New York City for most of its existence.

Liberation News Service distributed news to a wide range of audiences, including African Americans, factory workers, women, ethnic minorities, and high school students; and institutions like bookstores, libraries, community centers, and prisons. One of LNS' mandates was documenting contemporary social movements, including worker strikes in Ohio, miners' rights movements, and the Attica Prison riot. LNS went beyond domestic news, covering international events in Africa, the Dominican Republic, and Latin America. It offered extensive reporting on the Vietnam War, including the lives of people in both North and South Vietnam. LNS provides scoops on important stories, covering topics like torture in Vietnam and political corruption in San Diego before other major news outlets.

According to former LNS staffers Thorne Dreyer and Victoria Smith, the Liberation News Service "was an attempt at a new kind of journalism — developing a more personalistic style of reporting, questioning bourgeois conceptions of 'objectivity' and reevaluating established notions about the nature of news..." They pointed out that LNS "provided coverage of events to which most papers would have otherwise had no access, and... put these events into a context, helping new papers in their attempts to develop a political analysis... In many places, where few radicals exist and journalistic experience is lacking, papers have been made possible primarily because LNS copy has been available to supplement scarce local material."

The total combined circulation of the LNS-member papers was estimated to be in the millions.

Liberation News Service was founded in August 1967 by Ray Mungo and Marshall Bloom after they were separated from the United States Student Press Association and its Collegiate Press Service. Operating out of a townhouse at 3 Thomas Circle which they shared with the Washington Free Press, the LNS soon released its inaugural mimeographed news packet.

With support from private donors and assistance from the nearby Institute for Policy Studies, they were soon joined by other young journalists, including Allen Young, Marty Jezer, and photographer David Fenton, sending out packets of articles and photographs on a twice-weekly schedule to underground newspapers across the U.S. and abroad.

During this time the writings of Thorne Webb Dreyer — co-founder of the Austin, Texas, underground paper The Rag — were widely distributed, appearing regularly in dozens of periodicals. Dreyer's coverage of the October 21, 1967, March on the Pentagon – with its massive acts of civil disobedience – was distributed by LNS and published around the world. The night before the march, Bloom, Mungo, and the other staffers convened a chaotic meeting in a Washington loft with underground press editors from around the country who were in town to cover the event; but they failed to reach an agreement to create a democratic structure in which LNS would be owned and run by its member papers.

Operating on their own with a volunteer staff of 12, Bloom and Mungo moved forward with ambitious plans for the expansion of LNS. In December 1967 they opened an international Telex line to Oxford, England; and later that winter LNS merged with the Student Communications Network (SCN), based in Berkeley, California, which had its own nationwide Telex network with terminals in Berkeley, Los Angeles, New York, Ann Arbor, Ames, Iowa, Chicago, and Philadelphia, leased from Western Union. The Student Communications Network was a project of the University Christian Movement, a liberal Protestant church organization described as "mostly concerned with political and social issues rather than Christian evangelization."