Malcolm Gladwell in The New Yorker:
At Princeton, emissaries were sent to the major boarding schools, with instructions to rate potential candidates on a scale of 1 to 4, where 1 was “very desirable and apparently exceptional material from every point of view” and 4 was “undesirable from the point of view of character, and, therefore, to be excluded no matter what the results of the entrance examinations might be.” The personal interview became a key component of admissions in order, Karabel writes, “to ensure that ‘undesirables’ were identified and to assess important but subtle indicators of background and breeding such as speech, dress, deportment and physical appearance.” By 1933, the end of Lowell’s term, the percentage of Jews at Harvard was back down to fifteen per cent.
If this new admissions system seems familiar, that’s because it is essentially the same system that the Ivy League uses to this day. According to Karabel, Harvard, Yale, and Princeton didn’t abandon the elevation of character once the Jewish crisis passed. They institutionalized it.