The complexities involved in interpreting ethnicity are aptly demonstrated by the case of the u.s. Hispanic population. While their presence in the United States predates the emergence of the American nation, their numerical strength and national visibility resulting from a high birth rate coupled with continuing inflows of new immigrants presents a challenge for students of ethnic stratification. "Hispanic" as a label combines colonized natives and their offspring, foreigner and political refugees under one ethnic umbrella, but the coherence of this label is questionable on theoretical and historical grounds. Unlike the European immigrants of the nineteenth and early twentieth centuries, the majority of Hispanics have not become structurally integrated into the broader society. And, in contrast to other white immigrants, use of Spanish has not disappeared among the second or third generations reared in the United States. Today Hispanic enclaves and the Spanish language thrive in diverse regions of the country, although there is evidence of linguistic acculturation among all Spanish-speaking national origin groups who have lived in the United States over a generation.