The conclusion was, to say the least, surprising: a World Value Survey of people in 65 nations, conducted recently by an international group of social scientists and first reported in the British magazine New Scientist, decided that the world's happiest people lived in Nigeria. Those ranked second to fifth in the happiness survey were the people of Mexico, Venezuela, El Salvador and Puerto Rico. The findings defied conventional wisdom. Nigerians live in a volatile, poverty-stricken country. Could they really be more content than, say, proudly prosperous Americans, whose bountiful nation placed a dismal 16th on the list?

We Americans are told in our Declaration of Independence that three things are sacrosanct--"life, liberty, and the pursuit of happiness." And like fellow hedonists in Asia, Europe and elsewhere, we've clearly taken the message to heart. We work hard, earn lots of money and spend gleefully on iPods, flat-screen TVs, SUVs and all sorts of expensive fripperies. We indulge, we gratify--and therefore we expect to be the happiest damn people on the planet.

So why aren't we? Happiness is, of course, a subjective quality with links to genetics, health, personality, income level and expectations. The word "happy" is not easy to define and means different things to different people. Americans equate happiness with self-esteem and personal success, whereas for the Japanese, joy derives more from self-discipline and fulfilling one's obligations to family, company and community. When respondents in the World Value Survey were asked a second question--if they were "satisfied" with their lives rather than "very happy"--the results were much different. Developed nations jumped up in the rankings dramatically.

Despite the perils of trying to measure happiness, there are links between public policy and personal satisfaction. Unsurprisingly, people with jobs are happier than the unemployed. People with ample leisure time are perkier than those who have their shoulders to the wheel 60 hours a week. But the relationship between money and happiness can be tricky. Daniel Kahneman, a professor of economics at Princeton and co-winner of the 2002 Nobel Prize, says the notion that poorer people are happier than the wealthy is a myth. "People are more satisfied with their lives if their income is higher. They consider themselves more fortunate and more successful--more things have gone their way in life," he says. But he and other experts agree that a person's happiness level doesn't simply rise with his bank account; the law of diminishing returns applies. Indeed, research shows that contentment levels in developed nations have leveled off over the past 40 years even as per capita income averages have grown steadily.

How so? The answer, it turns out, is that happiness can be a tantalizing but elusive goal--a ripe apple in a tree that's always just out of reach. "Aspirations rise with income," notes Kahneman, and successful people can be unhappy if they perceive others in their peer group to be even more successful. John Helliwell, a professor of happiness economics (yes, that's his title) at the University of British Columbia, adds: "A lot of people think high levels of material satisfaction should produce happiness. They say, 'Gosh, I have everything and I'm not happy.' But of course they don't have everything."

Richard Layard, codirector of the Centre for Economic Performance at the London School of Economics, believes that "satisfying relationships" are a more important influence on one's happiness than income, which he argues is "not very important." As he sees it, a married man who does volunteer work is more apt to feel better about himself than a divorced career fanatic who's sweating out his next promotion. David Halpern, a senior consultant for a recent British study on the politics of happiness, adds that community trust is another key factor. He contends that happiness is largely determined "by how much a person trusts the other people in his or her community."

That idea is consistent with an unusual school of thought about happiness--that adversity can in some instances promote good feelings about oneself. A century ago the French founder of modern sociology, Emile Durkheim, argued that both natural and man-made disasters were good for societal happiness, because they gave people a chance to capitalize on "potential relationships"--in other words, to make new friends. That notion may explain why Nigerians who live in harsh circumstances can nonetheless experience joie de vivre.

But we can't be sure. As Aristotle once wrote, "Both the general run of man and people of superior refinement consider happiness the highest of all [states of being]. But with regard to what happiness is, they differ." For now, try working less and socializing more--without sacrificing your income. You're bound to feel pretty good.