There have always been anxieties among the American population about a perceived unwillingness of immigrants to become Americans. Ethnicity has been a phenomenon common to all immigrant groups. ‘The widening mainstream’ considers the issues that the United States has confronted related to the degree to which immigrants can be made to become Americans and the extent to which they feel themselves to be Americans. People are unable to live successfully, in comfort with themselves or with others, without a sense of continuity of self-understanding, personal relations, and self-worth. The United States has not always welcomed immigrants with enthusiasm, but its homogenizing social and political systems have created opportunities for them to become part of an American society that has gradually become more unified.