There are four main ways to invest in shares of companies based outside the U.S.:
American depositary shares (ADSs)
International stocks listed directly on U.S. exchanges
Mutual funds that invest internationally
Stocks listed on other markets
The first three approaches are so similar to investing in U.S. securities that you can follow the same selection process you do for choosing your domestic stocks and stock mutual funds. In fact, you may have already added an ADS or international stock listed on a U.S. exchange to your portfolio without actually thinking of it as substantially different from other stocks you own. Investing in Nokia may not seem like international investing if you use a Nokia phone.
Investing directly in other markets has the advantage of allowing you to choose equities that wouldn't otherwise be available, but it introduces a number of potential complications that you'll want to weigh before moving ahead.
Jeffrey Rosensweig, Goizueta Business School, Emory University
Jeffrey Rosensweig, Goizueta Business School, Emory University 
