In recent years, multiculturalism has become one of the popular terms. It has increasing influences on academia as well as on formulations of governmental policies. In Taiwan, the issue of multiculturalism is seldom systematically investigated. The principle of diversity has not been fully interpreted and implemented in library and information service. This article reviews related literature on multiculturalism, first to explore the origins and connotation of multiculturalism, and then to explain the relationship between multiculturalism and information service. Finally, the author suggests that Taiwan's libraries should develop a set of multicultural policies to serve a great diversity of readers.