Until recently, with one historical exception, America was able to take for granted a coherent national culture and identity. Successive waves of immigrants entered a country that assumed that their ultimate assimilation was a desirable, not an oppressive, outcome. The United States did not prove equally hospitable to everyone: some groups endured enormous hardships on their way to a fuller realization of America's great promise of opportunity and freedom. Yet, throughout U.S. history, the dream of common purpose and community propelled the collective desire to live up to this promise and provided the framework within which progress was understood and made.