Sussex School's founder, Bente Winston, has dedicated her career to promoting progressive education, both in her native Denmark
and in the United States. After teaching public school in Copenhagen for three years, Bente moved to Missoula in 1967. Interested in creating an innovative learning environment for her children, Bente connected with five other Missoula families in the summer of 1970, with the aim of founding a preschool that was a parent cooperative. A short time later, Bente and her husband, Don Winston, purchased a house at 212 West Sussex Street, and the Sussex Preschool officially opened its doors in January, 1971. By 1974, Sussex had expanded to twenty students from pre-K through 5th grade. The school purchased the building next door, and Sussex officially established itself as a non-profit parent cooperative school. By 1980, Sussex had thirty-six students in grades K-8.
In 1980, Sussex moved to its present location at 1800 South 2nd St. West, into the former home of Montana Governor Frank H. Cooney. The school quickly made a reputation for itself as one that offered a creative, child-centered curriculum. In 1988, Sussex received an Excellence in Education Award from the U.S. Department of Education. The same year, the eighth grade graduation was held in the school's new auditorium/gym facility, which had been built with the proceeds from a successful Capital Campaign.
Bente Winston remained head of Sussex until 1991, when Thom Sanders-Garrett became the school's new Director. Under Thom's leadership, Sussex continued to develop its reputation as an educational community that offers vital alternatives to more traditional schools. In 1992, Sussex received a "Breaking the Mold" award from the U.S. Department of Education. In 2001, the school launched its second Capital Campaign and added a spacious art studio, a new building with two large classrooms, and an attractive courtyard that brings the campus together amidst flowers, stone walkways, and trees. 
Robyn Reed Gaddy, the school's current director, came in in 2007. Under her tenure the school has become Montana's first L.E.E.D.*-certified school with two new buildings, inaugurated in 2011, which house an up-to-date science lab, seven classrooms, and a kitchen for the school's students and staff. The school's enrollment is at an all-time high of 115 students.
Sussex has entered the 21st century with a strong mission, one that upholds the school's original vision of combining a fun-filled learning environment with high educational standards. Sussex School, now a respected part of the Missoula educational landscape with over 200 graduates.