The Decline of Western Civilization is a 1981 American documentary filmed through 1979 and 1980. The movie is about the Los Angeles punk rock scene and was directed by Penelope Spheeris. In 1981, the LAPD Chief of Police Daryl Gates wrote a letter demanding the film not be shown again in the city.

The film's title is possibly a reference to music critic Lester Bangs' 1970 two-part review of the Stooges' album Fun House, for Creem magazine, where Bangs quotes a friend who had said the popularity of the Stooges signaled "the decline of Western civilization". Another possibility is that the title refers to Darby Crash's reading of Oswald Spengler's Der Untergang des Abendlandes (The Decline of the West). In We Got the Neutron Bomb, an oral history of the L.A. punk rock scene collected by Marc Spitz, Claude Bessy aka: Kickboy, claims that he came up with the title.

The film is the opening act of a trilogy by Spheeris, depicting music scenes in Los Angeles during the late 20th century. The second film, The Decline of Western Civilization Part II: The Metal Years (1988), covers the Los Angeles heavy metal scene of 1987–1988. The third film, The Decline of Western Civilization Part III (1998), chronicles the gutter punk lifestyle of homeless teenagers in the late 1990s.

In 2016, The Decline of Western Civilization was selected by the Library of Congress for preservation in the United States National Film Registry, being deemed "culturally, historically, or aesthetically significant".