Modernization changes the roots of happiness. In agrarian societies with little or no economic growth or social mobility, peoples’ options are severely limited and religion makes people happier by lowering their aspirations. Economic development and democratization bring changes conducive to happiness by giving people a broader range of choices in how to live their lives. Consequently, although within most countries religious people are happier than non-religious people, the people of modernized but secular countries are happier than the people of less-modernized but religious countries. The high correlation between life satisfaction and a society’s per capita GDP further suggests that development tends to bring rising happiness. By showing evidence from representative national surveys showing that happiness rose in in an overwhelming majority of the 62 countries, this chapter also challenges the notion that neither individuals nor societies can lastingly increase or maximize their happiness. This chapter also suggests that human happiness is not fixed but can be influenced by belief systems and social policies.