Departing from previous research that focused only on how ‘the Irish’ became White, this essay will instead explore how the color line was used to define and divide the Irish Diaspora in the United States. The color line will be used as part of a bifocal perspective on the Irish Diaspora, which examines how certain sections of the Irish Diaspora became White and how others became Black. This approach can provide critical insights into the workings of racial formations by highlighting the social and political nature of race and tracing the concept’s historical flexibility. A historical overview of the interactions between Irish American athletes and American sport is conducted to reveal many racial variations and tensions found within the Irish Diaspora. While sport has actively contributed to these Irish racial formations, it can also be used to challenge and transform the foundations of the racial formations that are currently found in American society.