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 also 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 market strategist at Morgan Stanley, so I'm inclined to hear him out. As for this "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 and so far this year, 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 was 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? When Professor 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. Last year, Bill Miller's famed Legg Mason Value Trust (LMVTX) fell uncharacteristically flat. And that's despite some 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! to Wal-Mart (NYSE:WMT) to Home Depot (NYSE:HD) struggled just to break even.

Clearly, Miller could have benefited from a bit more foreign exposure, especially among his top names. And he's not alone. International stock funds 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.

I settled for the iShares EAFE Index and the Vanguard Emerging Markets exchange-traded fund (ETF). Because I confess: I was reluctant to buy foreign stocks 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 serious investor and an expert on international markets. I wouldn't consider buying a foreign stock without checking with Bill first.

Need some help, too?
Fortunately, you don't have to cross the Atlantic for good advice anymore, either. Bill recently launched a unique investment newsletter service called Motley Fool Global Gains to help American investors like us profit safely from the explosive growth in overseas markets. If you already have some experience, don't worry.

Like I said, Bill's a serious investor. So, it's not exactly 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 miss out on the historic bull market in international stocks. 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 and Vanguard Emerging Markets, 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. You can get all Bill's Global Gains picks with your free trial. The Motley Fool has a disclosure policy.