1980
Becomes affiliated with the American Montessori Society (AMS)
1982
Accredited by the Independent Schools Association of the Central States (ISACS).
1983
Addition to the building to increase preschool, K/1 classrooms and administrative offices.
1984
School changes its name to Chesterfield Day School.
1987
Addition to the building to increase 2nd/3rd grade and 4th/5th/6th grade classrooms.
1989
Second ISACS evaluation/accreditation.