The United States is in the midst of its fourth major period of immigration. Today’s is the largest in absolute numbers, although not as a proportion of the total population. Unlike in previous times, today’s immigrants come from every inhabited continent and represent just about every country in the United Nations. As in previous periods of large-scale immigration, there is a profound ambivalence about the phenomenon among the American public. Historically, Americans have seen their own immigrant forebears through rose-colored glasses while raising serious concerns about the contributions of current immigrants and the extent to which they will assimilate our values, language, and experiences.