[5][6][7] Founded in 1976, Delphian primarily teaches children in grades 8–12, with most living on campus either full or part-time.

[10] In the fall of 1976, Delphian School opened on the site of a former Jesuit novitiate near Sheridan, Oregon.

[18][19] Delphian School uses Study Tech; techniques created by Scientology-founder L. Ron Hubbard and licensed through Applied Scholastics.

[7] The school is the location of Heron Books, which published textbooks and materials using Hubbard's educational techniques (the Delphi Curriculum).

The school participates in the Oregon School Activities Association's (OSAA) Northwest League, 2A classification, for girls and boys sports: basketball, tennis, cross country, track and field, boys soccer, volleyball, and cheerleading; and for such other activities as speech and debate, solo music, and choir.

[25][26] At the 2022 Mountain Valley Conference district track and field championship the girls team won multiple disciplines including the 100 and 200 meters, 300 hurdles, and 4×400 relay.