Phi Sigma Iota was founded in 1922 at Allegheny College in Meadville Pennsylvania by Dr. Henry W. Church, members of his department of languages, and advanced students who were meeting to discuss linguistic and literary matters. PSI became a national society when Beta Chapter was established at The Pennsylvania State University in April 1925. Less than a year later, Gamma Chapter at the College of Wooster followed them. With these three chapters as the nucleus of the national organization, the first convention was held in May 1926, at Allegheny College.
At a National Convention held at Bloomington, Illinois in November 1935, Phi Sigma Iota merged with Alpha Zeta Pi, a similar society west of the Mississippi organized by Dr. Etienne Renaud and his associates in the Department of Languages at the University of Denver in 1917.
In 1949, Phi Sigma Iota was voted membership into the US Association of College Honor Societies, the first language society to receive that honor.
In 1978, under the Presidency of Dr. Santiago Vilas, the Society expanded into the National Foreign Language Honor Society Phi Sigma Iota to honor outstanding achievements in any foreign language including Classics, Philology, Applied Linguistics, Comparative Literature, and Bilingual Education.
In 1982, the Society became the International Foreign Language Honor Society by installing its first Chapter in a foreign country at Universidad Regiomontana, Monterrey, Mexico.
Today the Society maintains approximately 180 local chapters in the US and at American University in Paris, France.