From 1876 to 1924--a period of free immigration--the mission of the American public library in its work with immigrants was to Americanize the immigrants by teaching them English and preparing them for citizenship. From 1924 to 1948--a period of restricted immigration--the mission of the American public library in its work with immigrants was to educate the adult immigrant and to internationalize the American community. Together, the public library and the immigrant community have shaped and perpetuated the national understanding of the value of ethnicity and internationalism to American society. The American public librarians took on the roles of advocates for immigrant rights, social workers, propagandists for the American way, and educators. At the end of the twentieth century, as at the beginning, Americans are still debating the place of immigrants in American society. Public librarians are now as they were then, going about their duties and responsibilities of providing advice and materials to help immigrants, legal and illegal, cope with everyday life in America. The American public library has remained a sovereign alchemist, turning the base metal of immigrant potentialities into the gold of American realities.