Isidore Isou, Amos (1953).
Lettrism, founded in the late forties by Isidore Isou , was as much a reaction against Andre Breton's dictatorial control of Surrealism (and Surrealism's movement away from its conceptual origins in Dada towards that of mysticism), as it was an attempt the get poetry back into people's lives and on the 'hit parade.' In his attempt to rewrite all of human knowledge, Isou had discovered that the evolution of any art was characterized by two phases: 'amplic' and 'chiseling.' In following the development of the art of poetry for example, Isou saw the Lettrist at the end of a long chiseling phase which had begun with Baudelaire reducing narrative in his poetry to anecdote, then Rimbaud disregarding anecdote for lines and words, Mallarmé reducing words to sound and spaces (particularly in Un Coup de Des), and finally the Dadaists destroyed the word altogether. Isou saw at the end of this phase the new beginnings of an amplic stage for culture, from which a whole host of new arts, ways of working, and social institutions would eventually spring, with Isou at the center of all creative work.
The Lettrist worked on the level of the letter at the heart of what they believed to be an experiential language that was to be the basis of their new culture. Their Lexique Des Lettres Nouvelles, for example was a sonic alphabet of a 130 or so sounds from which a new natural language was to spring from and from which they composed their poetry. Isou along with his chief lieutenant, Maurice Lemaitre, worked out a notational style that resembled that of traditional, 'common-practice' music, sometimes even with staffs, bar lines, and dynamic markings. Lettrist poetry was also often performed by choral groups.
Isidore Isou, The God's Diaries (1950)
Much of the bulk of Lettrist activities moved toward visual manifestations of expression in the later years, with a great deal of activity in painting and film . Splinter groups and expunged individuals groups such as the Ultralettrists, evolved into a political manifestation, first the Lettrist International in 1952 (Gil J. Wolman, Jean-Louis Brau, Guy Debord, and Serge Berna) and then Situationism (1957-1972). Much of the current interest in Lettrism comes from its connection with the Situationists.
The Situationist International had its origins in 1956 at the First World Congress of Liberated Artist. It was a meeting of several artists who had belonged a number of obscure radical European art groups in the fifties such as COBRA, a Belgian group of subversive Surrealists (another anti-Breton faction); The International Movement For An Imaginist Bauhaus -- an anti-Max Bill group who were upset that the Bauhaus had been restructured by Bill to be an academy where only technical instruction was to be given; and members from the Lettrist International, were Situationism first saw the light of day.
The Situationist International (SI) anaylsis about the rise of spectacle politics  and its subsequent effects on mass culture that has deep resonances with today's conceptions of hyperreality and postmodernism. The SI (and it's earlier manifestation as the Lettrist International (LI)) proposed a number of social critiques or 'situations' by which a new socio-political organization of world culture based around the ever-changing principles of contemporary art would take the place of the materialistic, worn-out economies of the past. Particularly, they proposed the concept of Unitary Urbanism based in the function and functionality of urban space as determined by psychogeography -- the study of the precise laws and specific effects of the geographical environment, consciously organized or not, on the emotions and behavior of individuals living in that environment.
The Situationists wanted a total transformation of the world into one that would exist in a constant state of revolution and newness, just as F. T. Marinetti had proposed a half a century before with his founding manifesto of Futurism. The two tools to perform such a transformation, were developed by the LI as détournement ('a theft of aesthetic artifacts from the Old World') and dérive ('to drift -- opening one's consciousness to the unconsciousness of urban space'). The détournement according to Guy Dubord and Gil J. Wolman, in their 1956 essay was to replace art. The dérive was to replace work: What the group meant to practice, Dubord said in 1959, looking back, was "a role of pure consumption" -- the total consumption of all the images and words of the past, the total consumption of the groups surroundings, and ultimately the total consumption "of its time" . Their analysis of a world existing as banalities which can then be removed from their references to be reconstructed as a harmony based in art harks back to Kurt Schwitters and his Merzbau.
By the nineteen sixties, the Situationists had faded into obscurity as a result of their own over self-involvement in pure consumption and had committed themselves to a life of permanent novelty. After many purges and personality conflicts, there was little left of the SI except for a small group centered around Guy Dubord, their chief theorist. Occasionally there was a mimeographed newsletter which gave an indication that the group still existed as a functioning entity. They would have probably slipped off into complete oblivion like so many other undistinguished radical art movements of this century, except for the notoriety brought to them by an odd set of circumstances.
In 1966, largely out of apathy from their fellow classmates, a group of five students gained posts in the student government at the University of Strasbourg. Bored with what they saw of 'relevant' education as well as the typical youth-group politics of the times, they got in contact with what remained of the Situationist International through their old post office box. They asked them what they could do to break the strangle-hold of apathy, banality and stagnation that they saw all around them. After repeated pleas to the SI who were neither interested nor responsive, the students were finally told to go write a critique of their status as students and the society they represented. Unable to do such a critique, an SI member, Mustapha Khayati, eventually wrote the critique for them.
On the Poverty of Student Life  concentrated a decade of Situationist thoughts, values, and theories into a twenty-eight page scathing satire against the university as being an institutionalized form of ignorance and made light of its professors, the government, the church, the family, the traditional left, the fascist right, the work ethic, modern culture, etc. It proposed to create at last a situation that goes beyond the point of no return.
Of course, all those ridiculed by the publication, denounced the act of its publication as a misappropriation of public funds and the betrayal of positions of public trust. The student leaders were summarily removed from their positions by a pernicious implementation of 'the rules' typical of those in power who are laughed at. However, this reactionary response created a situation and a chain of events which resulted in the Paris Strike of 1968. This general student-worker strike shutdown the city for several days and was the most serious crises to face the French government since World War II .
The analysis of the '68 Strike's existence and failure has colored a major thread in French thought since that time . However, a more well-known connection popularized in Greil Marcus's study of a 'secret history' of influences (beginning in the Middle Ages and working up through Dada) is where the Situationists are connected to Punk through Malcolm MacLaren's support of situ-inspired activities dating from the Paris uprising. MacLaren's later creation of the Sex Pistols, the rock band to destroy rock 'n roll, is seen as a translation of the Situationist point of view, as well as their slogans and iconography into a pop music venue . This connection whether metaphorical or actual has inspired curiosity and controversy , and is particularly ironic considering that the main intentions of the SI during their brief moment in time, was to mostly sit around a lot in bars and consume their environment. However, such interest has let to major retrospectives of their work, as well as all of their esoteric publications becoming readily available in several different translations, as well as a large archival site on the World Wide Web existing.