There are thousands of schools calling themselves Montessori in the United States, spread across public school districts, charter networks, and independent private schools, and no two are required to look alike. Some are led by teachers trained for years at AMI or AMS-accredited centers, using the full sequence of materials Maria Montessori herself refined. Others use the name loosely, with little formal training and few of the materials Maria Montessori herself refined. Telling the difference, and finding the right fit for your child and your budget, is the point of this guide.
What makes a school "Montessori"
"Montessori" was never trademarked by Maria Montessori or her heirs, which means any school, daycare, or homeschool co-op can put the word on its sign regardless of how closely it follows her method. That single fact explains most of the confusion parents run into when they start looking. The real signal of quality is not the name on the building but three things behind it: whether the school is affiliated with a recognized Montessori organization, whether its lead teachers hold credentials from a program accredited by MACTE (the Montessori Accreditation Council for Teacher Education), and whether the classroom actually uses the sequenced, self-correcting materials the method depends on.
The two organizations parents encounter most often in the US are AMI (Association Montessori Internationale, the international body founded by Maria Montessori's son Mario in 1929) and AMS (American Montessori Society, founded in the US in 1960). Both produce well-trained teachers and legitimate schools, but they differ in philosophy and training approach, which is worth understanding before you tour schools. The full comparison is covered in AMI vs. AMS: what's the difference.
Public or private: two very different paths
The most consequential decision most families make is not which accreditation a school holds but whether they are looking at public or private Montessori options, because the two differ enormously in cost, availability, and how much control the school has over its own curriculum.
Public Montessori programs, run as magnet schools or charter schools within a public district, are tuition-free and have grown substantially since the 1970s, with several hundred programs now operating across the country under the support of the National Center for Montessori in the Public Sector (NCMPS). They typically use a lottery for admission and must answer to state testing and curriculum requirements that can sit uneasily alongside Montessori's non-graded philosophy. Read the full picture in public Montessori schools.
Private Montessori schools charge tuition, ranging widely by region and prestige, but in exchange typically offer smaller classes, fuller fidelity to the AMI or AMS model, and freedom from state curriculum mandates. See private Montessori schools and what Montessori school actually costs for the details that matter to your budget.
Montessori by age and stage
Montessori schools are organized around distinct developmental planes, and what a classroom looks like changes substantially as children move through them. The Montessori preschool years (roughly ages two and a half to six, sometimes called the Children's House or Casa dei Bambini) are the most widely recognized stage, built around practical life, sensorial, language, and math materials in a mixed-age classroom. Montessori elementary (roughly six to twelve) shifts toward abstract reasoning, research projects, and the "cosmic education" curriculum that ties every subject back to the story of the universe. To see what an actual day looks like inside either stage, read a day in a Montessori school.
For the developmental theory behind each stage, the 0 to 3 years, 3 to 6 years, and 6 to 12 years guides go deeper into what changes in the child and why the environment is designed the way it is at each age.
Teaching Montessori: training, credentials, and pay
Behind every good Montessori classroom is a teacher who has completed a specific, rigorous training track, quite different from a conventional early-childhood education degree. If you are considering the path yourself, or simply want to understand what "Montessori-trained" actually means when a school uses the phrase, how to become a Montessori teacher walks through the credentialing routes, and Montessori teacher salary gives an honest picture of what the job pays across different settings and regions.
Explore Montessori schools in this guide
Start with the topic most relevant to your search, or browse Montessori options in major US cities:
The name tells you almost nothing on its own
Because "Montessori" isn't a protected term, the single most useful thing you can do before enrolling your child anywhere is ignore the sign out front and ask three questions: is the school AMI or AMS affiliated, are the lead teachers MACTE-trained, and can you observe an actual work cycle in progress. A school that can answer all three clearly is very likely the real thing. A school that can't is not necessarily bad, but it deserves a closer look before you commit.