This chapter assesses Althusser's contribution to the reconceptualization of ideology. Rather than offering a detailed exegesis, the chapter provides some general reflections on the theoretical gains flowing from Althusser's break with classical Marxist formulations of ideology. It argues that these gains opened up a new perspective within Marxism, enabling a rethinking of ideology in a significantly different way. Some of Althusser's propositions in the "Ideological State Apparatuses" essay have had a very strong influence or resonance in the debate. One influential proposition in the "Ideological State Apparatuses" essay is the insistence that ideology is a practice. There is something both profoundly important and seriously regretable about the shape of this "Ideological State Apparatuses" essay. The designation of ideologies as "systems of representation" acknowledges their essentially discursive and semiotic character. Often, ideological struggle actually consists of attempting to win some new set of meanings for an existing term or category, of dis-articulating it from its place in a signifying structure.