This book presents for the first time the correspondence during the years 1954 to 1978 between the Marxist-Humanist and feminist philosopher Raya Dunayevskaya (1910-87) and two other noted thinkers, the Hegelian Marxist philosopher and social theorist Herbert Marcuse (1898-1979) and the psychologist and social critic Erich Fromm (1900-80), both of the latter members of the Frankfurt School of Critical Theory. In their introduction, editors Kevin B. Anderson and Russell Rockwell focus on the theoretical and political dialogues in these letters, which cover topics such as dialectical social theory, Marxist economics, socialist humanism, the structure and contradictions of modern capitalism, the history of Marxism and of the Frankfurt School, feminism and revolution, developments in the USSR, Cuba, and China, and emergence of the New Left of the 1960s. The editors' extensive explanatory notes offer helpful background information, definitions of theoretical concepts, and source references. Among the thinkers discussed in the correspondence - some of them quite critically-- are Karl Marx, G. W. F. Hegel, Rosa Luxemburg, Georg Lukacs, Theodor Adorno, Max Horkheimer, Jean-Paul Sartre, Simone de Beauvoir, V. I. Lenin, Nikolai Bukharin, Sigmund Freud, Leon Trotsky, Mao Zedong, Daniel Bell, and Seymour Martin Lipset. As a whole, this volume shows the deeply Marxist and humanist concerns of these thinkers, each of whom had a lifelong concern with rethinking Marx and Hegel as the foundation for an analysis of capitalist modernity and its forces of opposition.