This volume is a revised and expanded version of a special issue of the journal October (Winter 1997) that was devoted to the work of the Situationist International (SI). The first section of the issue contained previously unpublished critical texts, and the second section contained translations of primary texts that had previously been unavailable in English. The emphasis was on the SI’s profound engagement with the art and cultural politics of their time (1957-1972), with a strong argument for their primarily political and activist stance by two former members of the group, T. J. Clark and Donald Nicholson-Smith. Guy Debord and the Situationist International supplements both sections. It reprints important, hard to find essays by Giorgio Agamben, Libero Andreotti, Jonathan Crary, Thomas Y. Levin, Greil Marcus, and Tom McDonough and doubles the number of translations of primary texts, which now encompass a broader and more representative range of the SI’s writings on culture and language. In a field still dominated by hagiography, the critical texts were selected for their willingness to confront critically the history and legacy of the SI. They examine the group within the broader framework of the historical and neo-avant-gardes and, beyond that, the postwar world in general. The translations trace the SI’s reflections on the legacy of the avant-garde in art and architecture, particularly on the linguistic and spatial significance of montage aesthetics. Many of the translated works are by Guy Debord (1932-1994), the impresario of the SI, especially known for his book The Society of the Spectacle.