After working as an assistant in her son's Montessori classroom, Mrs. Florence Johnson joined the second group of Montessori teachers to be trained in the Atlanta Area. After teaching for a few years, Mrs. Johnson was asked by several parents to open her own school in the Marietta area. In 1974, after recruiting additional students, securing a temporary location, and gaining Association Montessori Internationale (AMI) accreditation, Casa dei Bambini Montessori School was established with one Primary classroom of 28 children. One year later, the school — named after Dr. Maria Montessori's original school founded in 1906 in Italy — moved to its permanent home on Powers Ferry Road.

By 1987, Casa Montessori had grown to include four Primary classrooms and interest in an Elementary program had risen steadily among Casa's parents. There was sufficient demand to support a Lower Elementary program for 6-9 year olds. The Upper Elementary program for 9-12 year olds followed in 1990.

In 2011, Mrs. Johnson's daughter, Suzanne Johnson, stepped into her mother's shoes as Directress after obtaining her Master's Degree in Education from the University of Loyola, Baltimore. Suzanne carries on Florence's vision of a multi-cultural Montessori community that continues to nurture and grow. In 2014, Suzanne expanded Casa's program to include before and after school activities. And in 2015, Casa began its first Toddler program and offered an Extended Day Primary class for children under 5 years old.