Montessori de Terra Linda was founded in 1970 by June and John Lord, owners and founders of Ross Academy Montessori Schools.
Ross Academy began in 1963 and soon grew to include sites in Mill Valley, Ross, San Anselmo, Terra Linda, Novato and Petaluma. Montessori de Terra Linda opened in its current site, renting from Christ Presbyterian Church, in September, 1970.
Roberta Cummesky worked at the Mill Valley site in the after-school program, and in 1978, she became the assistant in the Primary program at the Ross site. Roberta and her husband, Jim Cummesky, took the Association Montessori International 3- to 7-year-old training in Perugia, Italy, in 1979, and returned in 1980 to teach at the Terra Linda site.
The Cummeskys took over Montessori de Terra Linda from Ross Academy Montessori Schools in 1981. They both taught and directed the school until May 1996, when the school became a non-profit organization. At this time, the Cummeskys were able to return to full-time teaching.
In 1980, MdTL included one Pre-Primary class of 18 children and one primary class of 35 children. A second Primary class was added in 1983, and a third Primary class in 1988. The school expanded to include the Elementary program in 1984. In 1985, the Elementary class and one Primary class moved up the street to the Santa Margarita School site. In 1994, additional classrooms at the current campus, Christ Presbyterian Church (CPC), became available, so the Primary and Elementary programs were moved from Santa Margarita to CPC to establish one unified school community.