I had a rather interesting experience this week appearing on the CNBC show, The Big Idea with Donny Deutsch. The theme was that being happy will bring you cash. Over the top? Absolutely. Ridiculously enthusiastic and fakely combative? Definitely. The people were all very nice though, and I had fun (even after the first segment, when the executive producer told everyone they were doing “a great job,” but then pulled me aside and ordered me “to amp it up”).

So, does happiness deliver dollar bills? Well, actually, the evidence suggests it does.

I’ll explain how, but allow me first to backtrack for a moment.

As an experimental social psychologist who has been studying happiness for almost 20 years, I’m often asked, “What makes people happy?” Until a few years ago, my answer always reflected the common wisdom and empirical findings in my field – “It’s relationships, stupid.” That is, I always responded that our interpersonal ties – the strength of our friendships, familial bonds, and intimate connections – show the highest correlations with well-being.

Imagine my surprise then, after Ed Diener, Laura King, and I conducted a meta-analysis (a “study of studies”) of 225 studies of well-being. I wholly expected to discover that social relationships – more than any other variable – would be both causes and consequences of being happy. However, what I observed was something rather different. One factor towered over relationships in its connection with happiness. That factor was work.

The evidence, for example, demonstrates that people who have jobs distinguished by autonomy, meaning and variety – and who show superior performance, creativity, and productivity – are significantly happier than those who don’t. Supervisors are happier than those lower on the totem pole, and leaders who receive high ratings from their customers are happier than those with poor ratings. And, of course, the income that a job provides is also associated with happiness, though we now all know that money has more of an impact when we have less of it.

Why does our work make us happy? Because it provides us a sense of identity, structure to our days, and important and meaningful life goals to pursue. Perhaps even more important, it furnishes us with close colleagues, friends and even marriage partners.

The story doesn’t end there, however. Studies reveal that the causal direction between happiness and work runs both ways. Not only do creativity and productivity at the office make people happy, but happier people have been found to be more creative and productive. They are better “organizational citizens” (going above and beyond their job duties), better negotiators, and are less likely to take sick days, to quit, or to suffer burnout.

The most persuasive data regarding the effects of happiness on positive work outcomes (as opposed to vice versa) come from longitudinal studies – that is, investigations that track the same participants over a long period of time. These studies are great. For example, people who report that they are happy at age 18 achieve greater financial independence, higher occupational attainment and greater work autonomy by age 26. Furthermore, the happier a person is, the more likely she will get a job offer, keep her job, and get a new job if she ever loses it. Finally, one fascinating study showed that people who express more positive emotions on the job receive more favorable evaluations from their supervisors 3.5 years later.

But the point that really interested Donny Deutsch and his producers is that all of this applies to income. Not only does greater wealth make people (somewhat) happy, but happy people appear more likely to accrue greater wealth in life. For example, research has demonstrated that the happier a person is at one point in his life, the higher income he will earn at a later point. In one of my favorite studies, researchers showed that those who were happy as college freshmen had higher salaries 16 years later, when they were about 37!

But before we find yet another reason to be envious of very happy people (not only do they get to feel great, but they get to have good jobs and make more money as well!), consider what the research on happiness and work suggests. It suggests that, when it comes to work life, we can create our own so-called “upward spirals.” The more successful we are at our jobs, the higher income we make, and the better work environment we have, the happier we will be. This increased happiness will foster greater success, more money, and an improved work environment, which will further enhance happiness, and so on and so on and so on.

If you want to learn more about the psychology of happiness and how people can become happier, I’m teaching a “master class” (via phone) on 7 Thursdays (1pm-2pm EST) starting July 24, 2008 (with a break in August).