The Montessori School of Duluth started as the Montessori Elementary School -- the first private, independent, nondenominational elementary school in the history of Duluth. It was founded in 1981 by Anne and Al Nephew to serve fifteen students graduating from a Montessori Children's House. The elementary classroom, originally located on Park Point, was taught by Anne who earned her AMI elementary diploma in Dublin, Ireland, her teaching license from St. Scholastica College, and her MA from the University of Minnesota.

The school was incorporated as the Montessori School of Duluth, Inc., a not-for-profit tax exempt corporation, in 1982. In 1983 it added the preschool Montessori program and moved to the Cathedral (now Marshall) High School campus.

In 1991 the school purchased property in Hunter's Park, a beautiful residential neighborhood in eastern Duluth. The new wing of the school was designed for small children, with spacious classrooms, kitchen, library, and playrooms. The outdoor areas were developed with shady fenced preschool play areas, raised bed gardens for flowers, fruits, and vegetables, and areas for older students.

By 2009 an enlargement and remodeling project was completed in the Early and Late Care area and the elementary school areas, creating an exceptional planned environment for our students.