From its prehistory in the biological theories of racial difference formulated in the 1800s to its current position in academic debate, Richard Rees investigates the diverse fields of scholarship from which the multifaceted understanding of the term ethnicity is derived. At the same time, Rees traces the broader historical forces that shaped the needs to which the concept of ethnicity responded and the social purposes to which it was applied. Centrally, he focuses upon the emergence of ethnicity in the early 1940s as a means of resolving contradictions and ambiguities in the racial status of European immigrants and its subsequent legacy and implications on race and caste. Shades of Difference introduces new perspectives on the definition of 'whiteness' in America, and makes an original contribution to the larger discussion of race through a detailed account of ethnicity's original meaning and its revaluation when later appropriated by the discourse of Black Nationalism in the 1960s and 70s. Rees has produced a powerful new analysis of the cultural and political history of ethnicity in America.