Some early members of the Cornell faculty became concerned about the quality of education available to such students and founded Cascadilla School to address this inequity.

However, students also pursued athletic activities such as football and crew and created yearbooks to record their activities.Shortly after the First World War, the school fell on hard financial times.

They were forced to sell several buildings and parcels of land, including the Cascadilla School Boathouse, which still stands and is the centerpiece of Stewart Park.

In the later part of the 20th century, headmaster Maxwell Kendall began to accept female students, created a board of trustees for the school, made Cascadilla independent of (although still affiliated with) Cornell University, obtained accreditation from the New York State Board of Regents, obtained not-for-profit status, and marketed the school to international students with great success.

Between 40 and 60 students from ten different countries are guided by a faculty of twelve teachers, many of whom hold advanced degrees.