In Sociological Theories in the 20th Century, José Maurício Domingues presents some of the vital interpretative keys to understanding any sociological theory. The concepts of unit of analysis, structure, and action, as well as memory and creativity, are central to the author's approach. Ideas and topics related to history, such as theology and contingency, are also present, as are those of social systems and evolution. Recurring themes of sociological theory are presented in a didactic manner, aimed at both laypeople and academics. The work offers a mature and critical reflection on contemporary society. José Maurício values certain aspects of current reality, points out flaws—when necessary—and reminds us: "The State, political parties, and capitalism were born from sociological thought itself. It is only natural that we return to it." José Maurício Domingues has a deep understanding of sociological theory and, in this brief essay, demonstrates how the sociologist views the world. The author engages with his reader in a debate about the future of sociology. As an interlocutor, José Maurício assesses the relationships between sociological theory and all fields of human knowledge. Sociological Theories in the Twentieth Century focuses attention on the works of some emblematic figures in sociological theory. The line of thought of each of these specialists is isolated and analyzed. By discussing their contributions and their impact on sociological theory, José Maurício Domingues immerses the reader in the world of modern sociology. José Maurício Domingues holds a PhD from the London School of Economics and Political Science and is a professor of Sociology at the Federal University of Rio de Janeiro (UFRJ). He is the author of Sociological Theory and Collective Subjectivity (1995), Social Creativity, Collective Subjectivity and Contemporary Brazilian Modernity, and Sociology and Modernity.