AMI vs AMS: What the Difference Means for Your Child

AMI and AMS are the two main Montessori associations in the US, and both train teachers and review schools. AMI, which Maria Montessori founded in 1929, gives teachers a diploma for one age level and recognizes schools mainly on classroom practice and teacher training, while AMS, founded in the US in 1960, credentials teachers through affiliated programs and accredits the whole school. For your child, the badge on the website matters less than the training of the teacher in their own classroom.

Where Do AMI and AMS Come From?

In the US Department of Education’s 2023-24 survey of private schools, NCES estimates that 1,188 schools belonged to the American Montessori Society (AMS) and 444 to the Association Montessori Internationale (AMI) (NCES 2026-015, Table C-14). Some schools belong to both.

Maria Montessori founded AMI in 1929 with her son Mario, and it is still based in Amsterdam. It runs teacher training around the world and works through national affiliates such as AMI/USA. AMS came later. Nancy McCormick Rambusch founded it in the United States in 1960, and today it reports members in 70 countries (AMS).

Both organizations follow Maria Montessori’s method. Where they differ in practice is in how teachers qualify and how schools are reviewed.

How Do AMI and AMS Train Teachers?

AMI training leads to an AMI diploma for one age level, from birth to 3, 3 to 6, birth to 6, 6 to 12 or 12 to 18. AMI prepares its own trainers, and courses run over one academic year, over several summers, or in modules. Every course includes observation and teaching practice (AMI), and students sit written and oral exams with examiners appointed by AMI. Entry requirements are set by each training center.

AMS works through affiliated teacher education programs run by colleges, universities and independent centers. Graduates earn an AMS credential. The full credential requires a bachelor’s degree. An associate credential, open to people with a high school diploma, exists only for the Infant & Toddler and Early Childhood levels. AMS says a credential typically takes one to two years, with in-person or blended coursework and a yearlong practicum (AMS). It does not affiliate fully online programs.

MACTE, the accrediting body for Montessori teacher education recognized by the US Department of Education, counts both AMI and AMS among its recognized organizations (MACTE).

For a parent, the practical point is that both routes involve serious, level-specific training. A teacher with an AMI primary diploma and one with an AMS Early Childhood credential have both studied the 3 to 6 curriculum in depth.

What Do Membership, Recognition and Accreditation Mean?

School websites sometimes use these words loosely, but each one means something different.

Membership

Membership is the entry point. A school pays dues and gets resources and support. AMS calls this the member school stage of its pathway, and membership alone involves no review of the classroom (AMS).

AMS Verification and Accreditation

These add outside checks. A verified school has shown AMS that it upholds five core components, namely trained teachers, multi-age classrooms, Montessori materials, child-directed work and uninterrupted work periods. Verification is renewed every three years. Accreditation goes further. The school writes a self-study covering its governance, curriculum, finances, facilities and outcomes, hosts a team of peers from other accredited schools, and waits for a decision from the AMS Board. Accreditation typically lasts seven years (AMS).

AMI Recognition

AMI’s review in the US focuses on the classroom. AMI/USA gives three statuses. A Recognized school has AMI-trained teachers in every classroom at that level and meets all AMI standards. Affiliated and Associated schools have a smaller share of AMI-trained teachers, and Associated also covers programs still working toward the standards. A consultant visits in the first year and every three years after that. Recognition looks at teaching and the environment and does not assess licensing, finances or administration (AMI/USA).

	AMI	AMS
Founded	1929, by Maria and Mario Montessori	1960, by Nancy McCormick Rambusch
Teacher qualification	AMI diploma for one age level	AMS credential, full or associate
Degree for teachers	Set by each training center	Bachelor’s for the full credential
School review	Recognition through AMI/USA	Verification, then accreditation
What the review covers	Classroom practice and teacher training	The classroom and the whole school
Review cycle	Consultation every three years	Accreditation typically lasts seven years

What Do the AMI and AMS Badges on This Directory Mean?

The AMS Member and AMI Member badges come from the federal Private School Universe Survey for 2023-24, which asks each school which associations it belongs to. Schools report their own membership, and the answer doesn’t show AMS accreditation or AMI recognition. To check those, search the AMS school directory, which may show a school’s pathway stage, and ask the school for its current AMS or AMI/USA status in writing.

The survey covers US private schools teaching at least one grade from kindergarten to 12th, or comparable ungraded classes, and runs every two years. Public Montessori schools, preschool-only programs and schools outside the US never carry these badges, even when they belong to AMS or AMI, and a school that joined or left an association since the survey won’t show the change yet.

Our Verified Montessori badge is separate. It means an official record, such as the US Department of Education’s private school survey, lists the school as Montessori. A school with no such record can still earn it when its own website describes it as Montessori and other signals agree, such as its name or web address.

Is AMI or AMS Better for My Child?

Neither association is a guarantee, and neither is a requirement for a good school. They answer different questions. AMI recognition says the most about teacher training, since its top status requires AMI-trained teachers in every classroom, while AMS accreditation is the review that sends an outside team to look at the whole school, including how it is run.

Some schools hold neither and still run strong classrooms. Some employ teachers from both training routes. What matters most for your child is the classroom you will actually use, with its teacher, its work period and its materials. Our guide on how to choose a Montessori school covers what to look for, and our tour checklist includes questions about training and affiliation. To check a specific campus, see is this Montessori school accredited.

For more on training levels and other organizations, see the certifications overview and the pages on AMI and AMS. When you’re ready to compare schools, find Montessori schools near you.