In trying to develop an objective standard in this study, Fishberg took anthropometric physical measurements of 3,000 New York City Jews. Ultimately, he concluded that differences between those identifying as Jews and those in the general population lay not so much in physical or anthropological characteristics as in their distinct political and social beliefs and mindsets. As these traits were changeable, especially through ever-increasing interfaith marriages, Fishberg found optimism in the possibility of ultimately obliterating all distinctions between Jews and Christians in both Europe and America. He does note this may prove deadly to Judaism, and he does not see the need for Jews to commit race suicide, as he puts it.
Fishberg could not have foreseen or predicted the Holocaust during which Jews were rounded up and exterminated in large part based on being seen as a distinct and separate race with certain obvious physical characteristics, though he was prescient in foreseeing Jewish assimilation in the United States. Taken in its own context, however, Fishberg's study serves as an excellent portrayal of beliefs based upon assumed racial differences at this pre-scientific time. This classic study will be of interest to students of Jewish history and the history of demography in the United States.