Sussex School was founded by Bente Winston, a Danish schoolteacher, as a progressive preschool that operated as a parent cooperative. The school opened its doors in January 1971 on Sussex Avenue and by 1974, had expanded to twenty students from pre-K through 5th grade.
In 1980, Sussex had thirty-six students in grades K–8 and moved to its present location at 1800 South 2nd St. West. Recognized for its creative, child-centered curriculum, Sussex School received an Excellence in Education Award in 1988 and a “Breaking the Mold” award in 1991 from the US Department of Education. In 2015, Sussex was ranked as one of the best fifty elementary schools in the US by The Best Schools organization.
Sussex School is a community of learners, educators, families, alumni, and friends. Over the years, the school has grown and now enrolls over 100 students. To fit the growing population, additional buildings and a courtyard have been added to the campus. Sussex School constructed the first two LEED-certified school buildings in the state of Montana.