Despite the common perception that most persons of Mexican origin in the United States are undocumented immigrants or the young children of immigrants, the majority are citizens and have been living in the United States for three or more generations. On many dimensions of integration, this group initially makes strides on education, English language use, socioeconomic status, intermarriage, residential segregation, and political participation, but progress on some dimensions halts at the second generation as poverty rates remain high and educational attainment declines for the third and fourth generations, although ethnic identity remains generally strong. In these ways, the experience of Mexican Americans differs considerably from that of previous waves of European immigrants who were incorporated and assimilated fully into the mainstream within two or three generations. This book examines what ethnicity means and how it is negotiated in the lives of multiple generations of Mexican Americans.