This document is the World Happiness Report 2015. It contains an introduction that discusses the history of happiness research and policy, including previous World Happiness Reports from 2012 and 2013. It notes growing interest from governments in measuring subjective well-being and using happiness research to guide policy. Several countries and local governments now explicitly aim to increase citizen well-being and happiness. The 2015 report will continue analyzing global trends in life satisfaction and well-being.