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

That, my friend, spells trouble
If this kind of thinking continues, we could be headed for some woeful underperformance, if not worse. 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 that title by consistently identifying trends that would have major impacts on global financial markets.

He even predicted 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 historic 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 was 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 making money overseas, we haven't missed the boat. In fact, when Wein last crossed the Atlantic to consult with his "source," he was even more adamant that we consider 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 unnamed "mystery man," how about a wizard from Wharton? When Professor Jeremy Siegel met with us here at Fool HQ last year, those were his exact words: "Global is definitely the way to go." More important, Siegel suggests that 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. Vanguard's respected U.S. Growth Fund (VWUSX), for example, managed a single-digit gain last year with hefty positions in Schlumberger (NYSE:SLB), Genentech (NYSE:DNA), and Google (NYSE:GOOG), among other marquee U.S. names.

Not even a record year and blowout finish from top-10 holdings Boeing (NYSE:BA) and Chicago Mercantile Exchange (NYSE:CME) could get the fund within 20 percentage points of the return offered by the MSCI EAFE internatioinal index. But it could have been worse. At least the Vanguard finished in the green.

Too many American superstars, from Yahoo! (NASDAQ:YHOO) to General Electric, struggled just to break even on the year. My point being that, like the rest of us, the fund could have benefited from a little foreign exposure. After all, international stocks and stock funds flat-out thumped their U.S. counterparts last year -- routinely delivering 20%-plus 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 here in the U.S. markets.

But you can't deny the fact that more than half the total capitalization of public companies already resides overseas, and that 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 that iShares EAFE Index. Because I confess: I don't have the expertise to invest in overseas stocks on my own. But 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 invest 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 an investment newsletter service called Motley Fool Global Gains to help All-American investors like us take advantage of the opportunities overseas. If you already have some experience, all the better. Bill's a serious expert. So, it's not exactly cheap to join.

But that's why this is such a valuable deal: You can try the service free for 30 days and pay nothing. If you don't love it, don't join. You won't pay anything. 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 about ths special trial, 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. Yahoo! is a Motley Fool Stock Advisor recommendation. The Motley Fool has a disclosure policy.