This chapter traces how ideas about happiness moved from ancient philosophy to modern institutions. It begins with classical Greek distinctions between hedonia (pleasure) and eudaimonia (flourishing), considers Epicurean tranquility and Stoic virtue, and notes Roman terms such as felicitas and beatitudo. Medieval Christian thinkers—especially Augustine and Aquinas—reframed happiness as union with God, reserving perfect happiness for the afterlife. Renaissance and Reformation debates reopened the place of earthly happiness, setting up Enlightenment shifts from salvation to reason, contract, and public welfare. The chapter then follows key figures: Rousseau’s inner balance, Locke’s “pursuit of happiness,” Hutcheson’s benevolence, and Bentham’s utilitarian calculus, alongside varied responses from Leibniz, Kant, and Schopenhauer. Nineteenth-century developments extend the story through Mill’s higher pleasures and industrial society’s competing promises of work, leisure, and family life. The early twentieth century’s consumer revolution recasts happiness as comfort, convenience, and choice. Together these strands move happiness from moral ideal to policy language, preparing the post-1950 turn to measurement, interventions, and well-being beyond gross domestic product.