In Europe during WW II gentiles opposed German policies and laws with respect to the annihilation of Jews at great risk to their own lives and the lives of their families. While anti-Jewish policies varied in their ruthlessness in different places and at different times, one thread remained constant: "each country under the German occupation had some people who risked their lives to protect Jews." Tec, Nachama. "Rescuers, Holocaust." Encyclopedia of Genocide and Crimes Against Humanity, Vol. 2, 2005, p. 895.

There are no exact figures regarding those who risked their lives to save Jews, though in 2004, Yad Vashem compiled a list of 20,205 gentiles and formally recognized them as "Righteous Among the Nations." Most researchers would agree that the actual number of rescuers is much higher. In any case, what can be agreed upon is that "practically all of the Jews who survived the war by living in the forbidden Christian world had benefited from some kind of aid" and that only a small minority of those who might have aided the Jews actually did. Ibid.

There were a variety of obstacles that prevented gentiles from aiding and rescuing Jews (or at least created problems that rescuers had to overcome before being able to aid and rescue). For example, it was forbidden by German law to offer aid to Jews and citizens were required by another law to report anyone known to be offering aid. Particularly in Poland, to offer aid to a Jew meant a death sentence if caught. In Western Europe, where the punishments were perhaps not as severe or as certain, still, a rescuer risked being sent to a concentration camp or even being murdered if caught. Finally, the extreme anti-Semitism prevalent at the time made many gentiles hostile to the notion of offering aid and comfort to the Jews. Some of those who eventually became rescuers have reported in interviews that they first had to overcome their own deep-seated, internalized anti-Semitism. Ibid.

In Nechama Tec's 1986 study When Light Pierced the Darkness, the author considered whether social class, amount of education, political involvement, degree of anti-Semitism, extent of religious commitment, and friendship with Jews had any bearing on (or predictive value for) who became a rescuer; he discovered that none of these characteristics were predictive of rescuer status. The results of the study, however, did point to six shared characteristics and motivations:

1. Individuality or separateness, an inability to blend into their social environments: Those who lived on the periphery of their community were less likely to follow the community's expectations or share its values, and therefore more likely to make the decision to aid and rescue.
2. Independence or self-reliance, a willingness to act in accordance with personal convictions, regardless of how these are viewed by others. 98% of the altruistic gentile rescuers in Tec's study identified themselves as independent.
3. An enduring commitment to stand up for the helpless and needy reflected in a long history of doing good deeds.
4. A tendency to perceive aid to Jews in a matter-of-fact, unassuming way, as neither heroic nor extraordinary. As Marie Baluszko, a peasant who aided many Jews, said, "What would you do in my place, if someone comes at night and asks for help? One has to be an animal without a conscience not to help." Still, 85% of survivors described their rescuers as "courageous."
5. An unplanned, unpremeditated beginning of Jewish rescue, a beginning that happened gradually or suddenly, even impulsively; and
6. Universalistic perceptions of Jews that defined them, not as Jews, but as helpless beings and as totally dependent on the protection of others. Ibid., pp. 897-898.

Most of the Jews who survived the Holocaust by living illegally on the Aryan side benefited from the aid offered by altruistic gentile rescuers. However, history also shows that there were rescuers who rescued for other reasons. For example, "paid helpers" were gentiles who aided and rescued Jews for money; as a purely commercial transaction, these rescues would not have happened without the payment of money to the rescuer. Other gentile rescuers included a group of previously open, avid anti-Semites who held themselves at least partly to blame for the German treatment of the Jews; they (mostly devout Catholics) hoped to atone for their sins by saving Jews from the systematic murder they felt partly responsible for. Finally, there is at least some evidence that Jews rescued other Jews, despite the fact that they themselves were targeted for annihilation. "There is concrete historical evidence of persecuted Jews who took on additional perilous duties to save others." Ibid., p. 898-899.