Language poetry was the first example of a self-professed Marxist avant-garde in the US since Objectivism, and the country's first nationally organised movement to overrun the institutions of poetry it assailed from its inception. Language writing continues to dominate Anglophone discourse around the politics of poetry, and its influence on the major current in political poetry today, the New Conceptualism, is direct and thorough. Its central figures (Charles Bernstein, Lyn Hejinian, Susan Howe, Ron Silliman, Bruce Andrews, Bob Perelman) have shaped poetic taste and practice, while its central ideas (the politics of poetic form, the materiality of language, the readerly production of meaning) remain important in the writing, reading and scholarship of poetry, in some cases becoming its naturalised doxa. But why did the 1970s give rise to a Marx-inflected, experimental poetics of Language? Why was Language the first example of a movement since the war, at a time when the idea of avant-garde grouping seemed moribund? Why has its effect on American poetry been so great? There are various keys to answering these questions: here I intend to examine the movement at its beginnings in the mid-seventies to its full emergence in Andrews and Bernstein's L=A=N=G=U=A=G=E magazine, exploring why commodification was so important to the movement's avant-garde positioning, its strategies for countering commodification and, within this, its attitude to audience. I will finally detail how Language eventually, into the mid-eighties and nineties, extricated itself from projects of direct political activism and avant-gardism, and how its formal discoveries were put to their fullest use outside of such projects. This will, of necessity, involve generalising the commitments of individual writers and placing them in a grouping many now deny ever existed. As a movement that constantly declared its political and avant-garde credentials, however, it will brook no other approach. If the achievements and interest of particular poets or poems is glossed over in what follows, it is only to throw the character of the wider phenomenon of ‘Language poetry’ into relief.