This book explores the relevance of key thinkers in social science from historical traditions to contemporary philosophers and the nature of modern society and how theories and concepts can be used to shed light on trends and inequalities around the world in which these thinkers lived. History is fast moving. The book attempts to explore the works of Weber, Durkheim, and Marx in the first three chapters to illustrate how their varieties of social science gave intimation about the social world in terms of social disorder and the remedies and actions needed to bring about social justice. The latter three chapters explore arguably the three most influential thinkers in social science of the 20th Century: Parsons, Foucault and Habermas. These thinkers in different ways gave a number of diagnoses of modern society. Some arguing for more balance between individuals and society as best regulated by institutions such as the family (Parsons), others argued for a more sophisticated understanding of power and how it plays out for social groups in modern society (Foucault) whilst for others critical social scientists should be focusing on defending the enlightenment ideals of reason and rationality as we go further into the 21st century. The book raises questions and provides many examples to stimulate thoughtful reflection about all our yesterdays, todays and tomorrows.