The Phi Beta Kappa Society (ΦΒΚ) is the oldest academic honor society in the United States, and is often described as its most prestigious honor society, due to its long history and academic selectivity.

Phi Beta Kappa aims to promote and advocate excellence in the liberal arts and sciences, and to induct the most outstanding students of arts and sciences at American colleges and universities.

It is founded at the College of William and Mary on December 5, 1776, as the first collegiate Greek-letter fraternity and is among the earliest collegiate fraternal societies.

Phi Beta Kappa (ΦΒΚ) stands for Φιλοσοφία Βίου Κυβερνήτης (Philosophia Biou Kybernētēs), which means "Love of learning is the guide of life".