First published in 1977, this book presents a comprehensive and lucid guide through the labyrinths of semiology and structuralism -- perhaps the most significant systems of study to have been developed in the twentieth century. The authors describe the early presuppositions of structuralism and semiology which claim to be a materialist theory of language based on Saussure's notion of the sign. They show how these presuppositions have been challenged by work following Althusser's development of the Marxist theory of ideology, and by Lacan's re-reading of Freud. The book explains how the encounter of two disciplines -- psychoanalysis and Marxism -- on the ground of their common problem --language -- has produced a new understanding of society and its subjects. It produces a critical re-examination of the traditional Marxist theory of ideology, together with the concepts of sign and identity of the subject.