As Cornish developed the idea of her school, she initially turned to the Montessori-based pedagogical method of Evelyn Fletcher-Copp,[5] but turned at last to the progressive musical pedagogy of Calvin Brainerd Cady, who had worked as musical director with John Dewey as the latter set up his seminal progressive educational project, what is now the University of Chicago Laboratory Schools.

[8][9] Nellie Cornish recruited opportunistically where she saw talent, and the school soon offered classes as diverse as eurhythmics, French language, painting, dance (folk and ballet), and theater.

[16] By this time, too, the school had expanded its age range, and was offering classes and lessons from early childhood to the undergraduate level.

"[22] Although the mortgage was paid off and the building had been donated to the school in 1929,[23] financial difficulties inevitably grew during the Great Depression.

[25] In December 2024, Cornish announced that it intended to merge with Seattle University and become the latter's flagship arts program when an agreement is finalized by May 2025.

Under the proposal, the two colleges would maintain their separate campuses in the city; Cornish would retain its 379,564 square feet (35,262.6 m2) of space for 500 students—a decline of 38 percent from peak enrollment in 2003.

Kerry Hall was designed in the Spanish Colonial Revival style by leading Seattle architect Abraham H. Albertson and is on the National Register of Historic Places (NRHP) as the "Cornish School".

The library at Cornish College specializes in art, dance, design, music, performance production, and theatre.