SAN JOSE, Costa Rica – An advertisement that greets passengers at the international airport here says, “Welcome to the happiest country of the world.” Inflated claim? Maybe, but a study indeed ranks Central America’s verdant nation of Costa Rica as the planet’s most content.

Its citizens generally live to old age, watched over by a government that spends heavily on schools and health care and strives to build an economy with a small environmental footprint.

Last month, Costa Rica beat out the United States and Western European nations for the second time to top a survey of 151 countries on a measure of progress and well-being, one that ignores the usual economic indicator – the gross domestic product, or the total amount of goods and services produced in a country. It ranked first in the Happy Planet Index put out by the New Economics Foundation, a British research center that promotes global well-being and sustainable development.

Some Costa Ricans downplayed or mocked the “happiest country” label even as a tourism campaign called the “Gift of Happiness” unfolded to attract new visitors from abroad. President Laura Chinchilla took the description lightly.

“We Costa Ricans have a strong spirit of self-criticism. We know our limitations, we are aware of our problems and, as free people, do not have a common definition of happiness,” Chinchilla recently told a U.N. forum.

Yet the idea of setting aside traditional, purely economic measures of development is provoking increasing global discussion, from a Happiness Initiative by the Seattle City Council to new ways to gauge growth in Europe and Asia.

The push reaches all the way to the United Nations, which hosted a conference in April titled “Happiness and Well-Being: Defining a New Economic Paradigm.”

Europe is taking note. In Britain, the government is experimenting with measuring “national well-being,” while the European Commission has a project called “GDP and Beyond.”

In compiling the Happy Planet Index, the New Economics Foundation said, it weighed three factors. First, it examined life expectancy (Costa Rica, at 79 years, tops the United States, where it’s 78.5 years). It then factored in a sense of well-being as measured in surveys that ask people to rate how they feel about their lives.

The last factor is environmental footprint, a per capita measure of the amount of land that’s required to sustain a nation’s consumption patterns.

The index doesn’t measure democracy or human rights, so Vietnam ranks No. 2 and Venezuela No. 9.