Perhaps understandably, Yugoslavia's image in the West has never been sharply defined. Most Americans know little more about the country than that Marshal Tito fought the Nazis, defied Stalin, and in 1948 pulled out of the Soviet bloc. But even the Yugoslavs have a blurred conception of themselves. In ethnic terms, there is no such thing as a Yugoslav. There are Serbs, Croats, Slovenes, Macedonians, and many other "nationalities." Although they share a common South (or Yugo) Slav origin,...