Pi Delta Phi (ΠΔΦ) is the National French Honor Society—La Société d'Honneur de Français—for undergraduate and graduate students at accredited public and private colleges and universities in the United States.

After many years as a local organization, Pi Delta Phi reorganized and declared itself the National French Honor Society in 1920.

The society expanded slowly during the next fifteen years but enjoyed renewed interest after World War II.

Regular members include undergraduate and graduate students at the sponsoring institution who are nominated in recognition of their academic achievement in French.

The official publication of Pi Delta Phi is À Vous l'honneur, the Society's newsletter.