Professor and Chair Catherine Ramírez wrote Assimilation: An Alternative History for the University of California Press in 2020. The book explores the history of the concept of assimilation in the United States. A pillar of the US nation-making project, assimilation is widely regarded as an outcome of immigration: it is the process by which immigrants turn into Americans. Ramírez decouples immigration and assimilation and probes the gap between assimilation and citizenship to show how certain social groups that are not immigrants or that are not recognized as real or legitimate immigrants have been assimilated as racialized and subordinate subjects.