ANY TRIP THROUGH a bookstore will reveal dozens of theories on how to be happy, many from pop-culture authors claiming to have found some hidden truth. "I love that popular books appear saying 'so and so reveals the secret of happiness,' " said Chris Peterson, a professor of psychology at the University of Michigan. "It is no secret."

Peterson is the program chair of this weekend's First World Congress on Positive Psychology and the co-founder of the field, which he defined as "the scientific study of what makes life worth living."

"Well-being" - a core focus of researchers - "is something greater than just feeling good," explained Deborah Swick, the associate executive director of the International Positive Psychology Association. "Positive emotions are a part of this, but that doesn't cover it to any extent."

Unlike many of the self-help tomes that claim to explore the same themes, positive psychology is a legitimate scientific discipline grounded in empirical research.

"We're not just up on a soapbox giving our two cents on the meaning of life," said Peterson. "We're trying to go out and do research and see what the facts of the matter might be."

Philadelphia - home to the world's first degree-granting program in positive psychology, at the University of Pennsylvania in 2005 - is generally considered the birthplace of the discipline, so it seems appropriate that the First World Congress will take place here.

"I think this is a really important next step for the field," said James Pawelski, who as executive director of IPPA watched membership leap from zero to thousands in the association's first year. "This will be the largest gathering of positive psychologists ever."

About 1,500 people are expected to attend the four-day confab which begins tomorrow at the Sheraton Philadelphia Center City, 17th and Race streets.

Presenters from all over the world will be speaking about several key areas of positive psychology, including the causes and effects of optimism, perseverance, enthusiasm and gratitude. The conference will also serve as a forum for practitioners, who apply these findings to a wide variety of fields like business, education, health, law, politics and - recently - peacekeeping.

Newer areas of research that will be discussed include the biological basis of happiness and character, the economics of well-being, the universal nature of happiness and the relationship between positive emotions and susceptibility to illness.

In some studies, positive psychologists subject conventional wisdom to the scientific method, rigorously testing the veracity of things we may take for granted. For example, what are the objective merits of gratitude?

"People say you ought to be grateful," said Ed Diener, a professor of psychology at the University of Illinois at Urbana-Champaign, "and we say: Well, if you're grateful, does it make you happier? Does it make other people happier?" (The short answer: yes.)

Diener, who will deliver the conference's opening remarks, has done a great deal of research into the relationship between happiness and money. It's of particular interest to people in the current economic climate, and, luckily, Diener's major conclusions indicate that ordinary belt-tightening does not lead to despair.

"True poverty, true unemployment - those are going to produce unhappiness," Diener explained. "But if your income goes from $100,000 to $50,000, you're on that part of the curve where it doesn't make much difference."

As long as basic needs for survival are met, Diener has found, people have a remarkable ability to adapt to their new circumstances.

"A lot of these changes in income are short-term in terms of the effect on your happiness," said Diener. "People throughout history have lived on a lot less income and been reasonably happy, so we can do it - it's just that adjustment."

For those who have recently been derailed from their career path of choice, studies about employment and happiness might offer some hope. Positive psychologists have found that with the exception of work environments that are emotionally damaging, a person's level of professional satisfaction is more closely tied to the individual than to the position itself.

"If you're enthusiastic, you're going to like your job whether you're a ditch digger or a Supreme Court justice," explained Peterson. "It's what you bring to the job."

So will the world congress be full of smiling, satisfied people, living what they've learned? "If you're handling radioactive materials, it's hard for you not to get infected with them," admitted Pawelski. "If you're handling well-being research and practice, it's hard for it not to rub off."

"It won't be moral saints grinning from ear to ear," said Peterson, dispelling oft-held stereotypes of people who work on happiness professionally. But he predicted that the First World Congress on Positive Psychology won't be quite like every other academic conference: "There will be a lot of hugging going on." *