Although happiness is based upon individuals' subjective perception of their own situation, understanding the concept of happiness is important for forming policies in modern societies. Taking into account discussions from disciplines across the social sciences, this book explores varying notions of happiness and how these are applied to create a theoretical understanding of the concept. The book then goes on to demonstrate how a general theoretical concept of happiness can be used to add to our knowledge of central aspects of modern society, ranging from questions related to welfare state analysis, through to evaluating everyday life for individual people. In doing so, Happiness presents an up-to-date and applied account of how happiness is now widely used in economics, sociology, psychology and political science, whilst also exploring the relationship between happiness and public policy.