This book provides a simple introduction to the economic analysis of the long period by means of Oded Galor's Unified Growth Theory. This aims at making Unified Growth Theory accessible for undergraduate students in Economics and the other Social Sciences. Using simple theoretical frameworks with or without microeconomic foundations, it shows how the major concepts of Unified Growth Theory – the economic regime, the regime shift, critical thresholds, latent dynamics – can be used to study the dynamics of societies over long horizons of time. Applications to the long-run dynamics of production, inequalities, institutions and the natural environment are examined.