SAN JOSE, Costa Rica -- 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 healthcare 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 United Nations 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. Taking cues from tiny countries such as Costa Rica and Bhutan, a Himalayan kingdom wedged between China and India, some experts seek to include social and environmental progress in measures of development.

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.”

“Gross national product has long been the yardstick by which economies and politicians have been measured. Yet it fails to take into account the social and environmental costs of so-called progress,” U.N. Secretary-General Ban Ki-moon said at the forum’s opening.

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.”

A Russian-born economist at the private National Bureau of Economic Research, Simon Kuznets, developed the concept of gross domestic product in 1934. The gauge uses the market value of all the goods and services a nation produces over a given period to measure its advancement. The measure had gained global acceptance by the time Kuznets picked up his Nobel Prize in economics in 1971.

But advocates of harmonizing development with environmental protection and social policies say GDP calculates destruction as if it were progress.

“When you pollute and clean up the pollution, GDP goes up. When you cut down the forests, GDP goes up,” Ashok Khosla, a Kashmiri who’s a Harvard-trained physicist and a leading expert on sustainable development, said in an interview. “GDP is a deeply flawed indicator.”