The Institute was founded in 1955 as the Monterey Institute of Foreign Studies by Gaspard Weiss, in collaboration with his wife, Louise Weiss, and cofounders Frank Elton and Sybil Fearnley. Weiss and his foreign language colleagues envisioned a graduate school that would promote international understanding through the study of language and culture.
In 1961, the school acquired its first building at 425 Van Buren Street, just up the hill from downtown Monterey. The structure, known today as the Segal Building, was built in 1911 as the Monterey Public Library.
In 2017, the Institute adopted a new mission statement:
The Middlebury Institute of International Studies educates professionals to advance understanding, promote peace, and drive change in pursuit of a more just world.