In a number of books on related topics - his titles included Ethnic America, Race and Culture, Conquests and Cultures and Affirmative Action Around the World -- Sowell shone a light on how educational and income disparities came to exist between different groups, and how politically successful minorities (like Irish-Americans, who dominated America's big cities as well as the hierarchy of the Catholic Church) sometimes lagged behind others in material terms while politically marginalised groups like the (Chinese diaspora in southeast Asia or the Jews of America) thrived economically and educationally.

Unsurprisingly, this did not endear him to politicians and activists who owed their positions and incomes to maintaining the view that income disparities were always the result of discrimination, which they of course maintained could only be addressed by political action.