This book is a complete presentation of the most important themes of Theodor W. Adorno's critical theory, and of its relevance for the understanding of the modern society. After an Introduction, which traces Adorno's biographical and intellectual profile, the book is structured in three parts. The first is devoted to theoretical philosophy, and in particular to the concepts of philosophy, negative dialectics and metaphysics, and his aim is to clarify the Adornian understanding of such difficult concepts. The second is devoted to the main themes of Adorno's social theory: the concept of domination, the relationship with Marxism, the theory of the decay of the individual, the critique of mass manipulation. The third part is devoted to aesthetics and culture criticism, and entails a conclusion in which the author outlines a confrontation between the Adornian and the Habermasian critique of modernity.