Rather than asking about whether immigrants and their descendants come to resemble the “mainstream”, this research places the acquisition of a new national identity among immigrants and their descendants at the center of attention. We contend that becoming “American” entails adopting American attitudes towards persons beyond the territorial divide, a population that includes nationals of one’s country of origin or ancestry. We begin by developing a conceptual framework to understand how attachment to the people of the state of emigration gets transformed into attachment to the people of the state of immigration. We then provide a demonstration of that process, focusing on Mexican immigrants and their descendants. We use a variety of data sources to highlight and unpack both of the different dimensions of Americanization, doing so in three steps. We start by focusing on American identity, examining the degree to which immigrants and their descendants explicitly identify as Americans and express pride in their American identity. With the view that commitment to some level of restriction is a fundamental attribute of commitment to the national community we then analyze views towards immigration policy, examining the links between patriotism, identification and attitudes towards immigrant rights and immigration.