[JonnieCache]

It's not a company, it's a teaching method/movement. The word Montessori is the name of it's originator (died 1952,) and it is used freely by anyone who uses the method:

In 1967, the US Patent Trademark Trial and Appeal Board ruled that "the term 'Montessori' has a generic and/or descriptive significance."[24] Therefore, in the United States and elsewhere, the term can be used freely without giving any guarantee of how closely, if at all, a program applies Montessori's work. The ruling has led to "tremendous variation in schools claiming to use Maria Montessori’s methods."[25]

https://en.wikipedia.org/wiki/Montessori_method#Use_of_Monte...

[thejteam]

Some states have additional regulations on who can call themselves "Montessori". For example, Maryland requires schools using the name "Montessori" to be approved by a "Montessori Validating Organization" that the state recognizes.

http://www.marylandpublicschools.org/msde/nonpublicschools/m...