In 1950, Debord began his association with the Lettrist International, which was being led by Isidore Isou at the time. The Lettrists were attempting to fuse poetry and music, and were interested in transforming the urban landscape. In 1953 they mapped out what they called the "psychogeography" of Paris by walking through the city in a free-associative manner, or "drifts". Texts on this activity were first published in Naked Lips in 1955 and 1956, in essays titled "Detournement: How to Use" and "Theory of the Derive."
In 1957 the Lettrist International joined another group of avant-garde artists, called Movement for an Imaginist Bauhaus, to form the Situationist International (SI), and founded the magazine called Situationiste Internationale. Debord proclaimed himself the leader of the SI, and saw himself responsible for maintaining the high ideals he had in mind for the group, but to equate Debord with the SI in all its activities would be misleading. He had a major role in unifying Situationist practice, but he also prevented its expansion into areas he felt would undermine his own goals.
The original membership of the SI were Parisian intellectuals and artists who were influenced by the Dada and Surrealist movements, and the group never grew to more than a dozen members. Members were rapidly admitted and expelled, and by 1963 all the original members had left or had been pushed out, including Asger Jorn, who was one of the most prominent members. At the beginning of the SI movement their goal was to transgress the boundary separating art and culture from the everyday and make them part of common life. They theorized that Capitalism has the effect of diverting and stifling creativity, dividing the social body into producers and consumers, or actors and spectators. The SI saw art and poetry as a production by all people, that this was a way to make art the dominant power rather than having power rest in a small group of designated men. They argued for complete divertissement, and were against work. By 1962 they were applying their critique to all aspects of capitalist society, and no longer limiting it to arts and culture. They were inspired by the history of the anarchist movement, and looked to the First International, Spain, Kronstadt, and the Makhnovists in their research. They accused the USSR of being a "capitalist bureaucracy", and were advocates for workers' councils. They retained, however, Marxist elements and never identified as entirely anarchistic.
In 1967 Debord published Society of the Spectacle, his major work. In the book he takes the position that the spectacle, or the domination of life by images, has subsumed all other forms of domination. He attacks wage labor and commodity production, indeed all forms of hierarchy, in an elaboration of Situationist theory, but claiming that they continue to wield power only in their subsumption into the spectacle. He writes that the spectacle is "capital to such a degree of accumulation that it becomes an image" and that images are the currency of contemporary society. Society of the Spectacle had an enormous influence on the student rebellion in 1968. Many quotations were taken from the text to become graffiti on the walls of Paris at the time. Members of the SI acted with the Enrages from Nanterre University in the assembly held in permanent session: the Occupations Committee of the Sorbonne. In 1973 Debord made a film version of Society of the Spectacle (Simar Films) and in 1989 he updated the text in Commentaries on Society of the Spectacle, proving its holding power as a definitive text on cultural imperialism, capital, and mediation in society.
The analysis that life has been reduced to a spectacle, as the result of all relationships becoming transactional in capitalist society, can be seen as a reworking of Marx's early writing on alienation. The Situationist addition to this theory is the recognition of "pseudo-needs", created by capitalism to continually ensure increased consumption. They switched consciousness from its determination at the point of production to the point of consumption, seeing modern capitalism as a consumer society. The individual, or worker, is no longer recognized as a producer, but courted as a consumer.
The Situationists believed that it was necessary to think of the immediate moment as the highest potential for change, and that to liberate oneself was to transform society by effecting power relations. They believed that to transform the structure of society we need only change our perception of the world. Their praxis was based in constructing situations that were disruptive to social norms. It was in this spirit that they created the idea of the 'derive,' as a flow of acts and encounters, and the 'detournement,' as a redirection of images and events. As methods of undermining consumer society and the constructed spectacle they encouraged vandalism, wildcat strikes and sabotage, seeing these as creative acts. The SI saw it their responsibility to make apparent to the masses the system in which they were already implicated. They hoped to be catalysts in a revolutionary process that would eventually make the SI redundant and cause their dissolution. This fantasy was not to come about, however, as the group disbanded over tactical disputes in 1972. Their ideas continue to have a lasting influence on art, politics and philosophy.
In 1971 Debord became friends with Gerard Lebovici, who would become his publisher and producer. In 1984 Lebovici was assassinated, and Debord was tangentially implicated. He was subjected to police interrogation, and suffered defamation in the press. Debord was infuriated by the accusations, and as a consequence, prohibited the screening of his films in France during his lifetime. He won his subsequent libel suits, and he published Considerations on the Assassination of Gerard Lebovici in 1985.
In 1987 Debord wrote The Game of War with his second wife, Alice Becker-Ho. In 1989 he published his Commentaries on the Society of the Spectacle, expanding on the earlier text by writing of the "integrated" spectacle, the new, more insidious form of the spectacle. In 1994, Debord committed suicide in Champot, Upper Loire. It was not his first attempt, having tried to asphyxiate himself once before in 1955. His ashes were scattered on the point of Ile de la Cite, Paris. The French press promptly made him a celebrity, never before having acknowledged the significance of the Situationist International or Debord's work.