According to the National Association of Investors, just one in three Americans feels "comfortable" investing in foreign stocks or bonds.

And that, my friend, spells trouble
If this kind of thinking continues, hardworking Americans like us could be headed for some woeful underperformance, if not disaster. Or so says "the smartest man in Europe."

The smartest who in what? I know, that's what I said! But that's what Byron Wein calls him. According to Wein, this mysterious chap earned his title by consistently identifying trends that would have major impacts on global financial markets.

This guy even called the collapse of communism and the dismantling of the Berlin Wall, or so the story goes. And yes, he warned us to start looking for stocks abroad long before the recent bull market in foreign stocks.

You think I've lost my mind, don't you?
In my defense, I read this in The Washington Post and Byron Wein is no hack. He spent years as a top equity analyst at Morgan Stanley. So, I'm inclined to hear him out. As for his "mystery man" on the ground ... who cares? Just look at the numbers.

In 2005, stock markets in countries as diverse as Egypt, Russia, Turkey, South Korea, and Austria all gained 50% or more -- dwarfing U.S. stocks. Just about the same thing happened in 2006, too. I don't know about you, but I'm starting to sense a long-term trend.

In other words, when it comes to global investing, we haven't missed the boat. In fact, when Wein last crossed the Atlantic to consult with his "source," he found him even more adamant than ever that we start moving some of our investments overseas. For what it's worth, I'm taking him up on it.

"Global is definitely the way to go"
If you'd rather not trust your future to some "mystery man," how about a Wharton professor instead? When Jeremy Siegel met with us here at Fool HQ last year, those were his exact words. More important, Siegel insisted we should hold as much as 40% of our portfolios in foreign stocks.

I wish I'd listened. I imagine some U.S. fund managers agree. Bill Miller's famed Legg Mason Value Trust (LMVTX), for example, was uncharacteristically below average last year. And that's despite (or maybe because of) the appearance of surprising names such as Sprint Nextel (NYSE:S), Qwest (NYSE:Q), and even (NASDAQ:AMZN) of all things, among his top holdings.

In the end, not even a strong finish from JPMorgan Chase (NYSE:JPM) could bail Miller out. But it could have been worse. At least Miller finished in the green. Too many American standards, from Yahoo! (NASDAQ:YHOO) to Wal-Mart (NYSE:WMT) to Home Depot (NYSE:HD) struggled just to break even..

I haven't broken down the entire portfolio, but it seems safe to assume that Miller could have benefited from a bit more foreign exposure, especially among his top names. The fact of the matter is international stock funds flat-out thumped U.S. funds last year -- routinely delivering 20% gains and, in many cases, much more.

Born on the fourth of July
I assure you, I'm not some doomsayer prophesizing the collapse of the West and the rise of "Chindia." I have too much faith in America for that ... and too much invested in the U.S. markets.

But it's also a fact that more than half the capitalization of all public companies already resides overseas. And just last year, investors poured $53 million into foreign large-company funds, up 32% from the year before. And, yes, I'm one of them.

So far, I've settled for the iShares EAFE Index. Because I confess: I'm too chicken to invest overseas on my own. But now I have a mystery man on the ground, too -- a Bill Mann, to be specific. If you don't know Bill, he's a globetrotter and an expert on international markets. I don't move a penny overseas without checking with Bill first.

Need some help, too?
Fortunately, you don't have to cross the Atlantic for good advice, either. Bill recently launched a unique investment newsletter service called Motley Fool Global Gains to help American investors like us get invested overseas. If you already have some experience, don't worry. Bill's a serious expert. So, it's not cheap to join.

But you can try the service free for 30 days and pay nothing. Of course, you won't actually go broke if you don't invest overseas. But it could cost you some serious money. Why not take Bill up on his free trial offer and try Global Gains, instead? To learn more, click here.

This article was originally published on Jan. 17, 2007. It has been updated.

Fool contributor Paul Elliott owns shares of the iShares EAFE index, but no other security mentioned. and Yahoo! are Motley Fool Stock Advisor recommendations. JPMorgan is an Income Investor pick. Wal-Mart and Home Depot are Inside Value selections. The Motley Fool has a disclosure policy.