Americanization is the process of an immigrant to the United States becoming a person who shares American culture, values, beliefs, and customs by assimilating into the American nation. This process typically involves learning the American English language and adjusting to American culture, values, and customs.

The Americanization movement was a nationwide organized effort in the 1910s to bring millions of recent immigrants into the American cultural system. 30+ states passed laws requiring Americanization programs; in hundreds of cities the chamber of commerce organized classes in English language and American civics; many factories cooperated. Over 3000 school boards, especially in the Northeast and Midwest, operated after-school and Saturday classes. Labor unions, especially the coal miners, (United Mine Workers of America) helped their members take out citizenship papers. In the cities, the YMCA and YWCA were especially active, as were the organization of descendants of the founding generation such as the Daughters of the American Revolution. The movement climaxed during World War I, as eligible young immigrant men were drafted into the Army, and the nation made every effort to integrate the European ethnic groups into the national identity.

As a form of cultural assimilation, the movement stands in contrast to later ideas of multiculturalism. Americanization efforts during this time period went beyond education and English learning, into active and sometimes coercive suppression of "foreign" cultural elements. The movement has been criticized as xenophobic and prejudiced against Southern Europeans, though anti-German sentiment also became widespread after the U.S. declared war on Germany.