Leonard B. Glick offers a history of Jewish and Christian beliefs about circumcision from its ancient origins to the current controversy about the ethics of performing such surgery on helpless infants. Things changed dramatically in the 19th century, he shows, when after nearly two millennia of attacking the practice, non-Jews began to laud its health benefits. By the turn of the century, more and more physicians in America and England (but not, interestingly, in continental Europe) were performing the procedure routinely. Glick shows that Jewish American physicians were and continue to be especially vocal and influential champions of the practice which, he notes, serves to erase the visible difference between Jewish and gentile men and boys. Informed medical opinion is now unanimous that circumcision confers no benefit and the practice has declined somewhat. Nevertheless, it is still routine in many hospitals, and more than 60% of all boys born in America are circumcised at birth. In Jewish circles it is virtually taboo to question circumcision, but Glick does not flinch from asking whether this disfiguring surgical procedure should really continue to be the defining feature of modern Jewish identity.