American undergraduate honorary society. Founded in 1776, election to it is considered by many the highest honor that can be granted to an undergraduate. Membership is granted to around 1% of college graduates.

Famous Phi Betes include:

PBK began as a secret literary and philosophical society at the College fo William and Mary; chapters were established in the early 1800s at other prestigious east coast institutions. The "secret" bit was jettisoned during a period of strong anti-Masonic sentiment, in 1831. PBK was the first greek-letter fraternity.