The World Happiness Report measures "subjective well-being" - how happy the people are, and why.
Denmark, Iceland, Switzerland and and Finland round out the top five, while the Central African Republic came last.
Western Europe and North America dominated the top of table, with the US and UK at 14th and 19th, respectively.
Countries in sub-Saharan Africa and those hit by conflict have predictably low scores. Syria placed 152 of 155 countries - Yemen and South Sudan, which are facing impending famine, came in at 146 and 147.