Phi Beta Kappa, or ΦBK, is a national honor society for students of the liberal arts and sciences. Students at the College of William and Mary created Phi Beta Kappa in 1776. The next chapters were created at Harvard and Yale, where Phi Beta Kappa remained a secret society until 1831. Today, there are 286 chapters of Phi Beta Kappa.

Reed created its Phi Beta Kappa chapter in 1938. Historically, Reed has not allowed Greek letter organizations, so the establishment of a Beta of Oregon chapter was somewhat contentious. Eventually, the school balanced its distaste for grades and labels with its appreciation for the Phi Beta Kappa principles by limiting the length and publicity of initiation into PBK. Many schools award PPK membership to both juniors and seniors, but Reed does not nominate students until graduation.