Natavism- an attitude among Americans of opposition towards ""foreigners"" and their institutions as well as towards anything ""different""- is explored and analysed, traced and projected imaginatively in all its weltering facets. The causes of natavism strike deep economically, touching upon the questions of presumed national self-interest and the composition of capital and labor groups; natavism spreads through the social fabric, affecting the laws on immigration, leading to segregation and ""protected"" areas, the founding of such orders as the Ku Klux Klan; its political roots reach into the problem of ""radicalism"", the so-called democratic ideal, as well as eugenic programs. The author believes that ""in early America the most powerful of the anti-foreign traditions came out of the shock of the Reformation,"" but he follows the entire evolution of natavism, with all its changes and reversals. The approach, utilizing the evidence of history, the framework of sociology, the broader insights of psychology (especially the kind of thinking for which the late Kurt Lewin was distinguished), is nevertheless suprisingly free of academic bias- or what might be called academic ""natavism"". A valuable contribution to our understanding of the nature of prejudice and human conflict.