From the middle of the 1940s onwards, Sartre became the personification of the committed intellectual, courageously taking public positions on many of the pressing issues of his time. In the 1950s and 1960s, the theoretical basis for his political commitment lay in his existentialist brand of Marxism, which received its most mature formulation in the "Critique of Dialectical Reason." Focusing on the point of departure for later Sartrean thought and political commitment, Sam Coombes highlights key areas of common ground between the ethical, aesthetic, and political content of works from Sartre's early period and classic Marxist philosophy. Taking account of both the specificity of early Sartrean thought and the heterogeneity of Marxist theories, this book affirms their lasting importance to radical left critique. It offers in-depth analysis of areas of early Sartrean thought hitherto rarely discussed in the literature such as the conceptual parallels between the concepts of inauthenticity and ideology, the political implications of Sartre's pre-war writings, and the first clear signs of Marxist tendencies in Sartre's wartime writings.