Pi Beta Phi (ΠΒΦ), often known simply as Pi Phi, is an international women's fraternity founded at Monmouth College, in Monmouth, Illinois on April 28, 1867, as I. C. Sorosis, the first national secret college society of women to be modeled after the men's Greek-letter fraternity.

Pi Beta Phi is one of 26 international sororities which are members under the umbrella organization of the National Panhellenic Conference.

"[4] They planned their society at a home where two of the women rented a room, choosing I. C. Sorosis as the name and "Pi Beta Phi" as the motto.

[5] Shortly after the founding, the sisters had a jeweler design their official badge: a golden arrow with the letters "I. C." on the wings.

In the 1960s, G. William Domhoff, writing in Who Rules America?, listed Pi Beta Phi as one of "the four or five sororities with nationwide prestige.

The Kansas Alpha chapter began publication of The Arrow in 1885; it would eventually become a quarterly magazine published by the international fraternity for all its members.

In order to do so, Pi Phi has started a reading enrichment program for students in pre school through third grade called, "Champions are Readers".

An extension of the Pi Beta Phi Settlement School called the Craft Work Shop was begun in 1945 in cooperation with the University of Tennessee.

The tone of the e-mail—with lines such as "No muffin tops or camel toe" and "I will not tolerate any gross plastic shizz [jewelry]"—drew criticism from the Huffington Post and many online young adult forums.

[16] In 2010, the chapter at the Miami University was suspended for one year after underage drinking, vomiting, littering, and damaging Lake Lyndsay Lodge in Hamilton, Ohio.

[17] In August 2017, the organization closed its chapter at Miami, saying that "... the decision was made because the membership experience has routinely fallen below Fraternity expectations, particularly in regards to risk management and the lack of commitment to Pi Beta Phi's core values.

[19] In 2013, the chapter at the University of Nevada at Reno was banned from campus until the last active member graduated due to repeated hazing violations.