Book excerpt: Salins argues that assimilation is part of a larger American social compact that has flourished throughout our history, and to abandon it now would destroy the foundations of our prosperity, our social cohesion, and, ultimately, American culture itself. He shows how successive immigrant populations have become Americanized, despite being considered "alien" in their time-notably, the Germans, Irish, Italians, and Jews-and how assimilation continues to work today among Hispanics and Asians. The book sheds light on the threats to assimilation from the left (multiculturalism) and the right (nativism), revealing the perilous consequences of each.