AMI vs. AMS Montessori: What's the Difference?
How to Tell if a School Is Truly Montessori
By Stephanie Woo, Head of School, Ms Lam Montessori
Table of Contents
Why the Montessori Label Alone Means Nothing
What AMI Actually Is
Why AMI Teacher Training Is Different
What Does It Take to Become an AMI Montessori Teacher?
What was Ms. Lam’s AMI Montessori Training like?
What was Stephanie’s AMI Montessori Training like?
Why Fidelity to the Method Matters
Montessori-Inspired vs. Authentic Montessori
What to Look For When Visiting a Montessori School
How Ms. Lam Montessori Applies AMI Standards
Frequently Asked Questions
The Bottom Line
Why the Montessori Label Alone Means Nothing
One of the biggest surprises for many parents is that "Montessori" is not a protected term in the United States.
Two schools can sit across the street from one another, both call themselves Montessori, and offer completely different educational experiences.
That's because "Montessori" is not a protected term in the United States.
For parents, this creates a difficult challenge: how do you know whether you're seeing authentic Montessori or simply Montessori-inspired education?
The answer often begins with one question:
Who trained the teachers?
What AMI Actually Is
AMI (Association Montessori Internationale) and AMS (American Montessori Society) are the two main Montessori credentialing organizations in the United States. AMI was founded by Maria Montessori herself in 1929 and maintains the strictest fidelity to her original method. AMS was founded in 1960 and takes a broader, more flexible approach. Both prepare qualified Montessori educators. The key difference is how closely each adheres to Montessori's original principles.
AMI stands for Association Montessori Internationale, the organization founded by Dr. Maria Montessori herself in 1929. Its mission is to preserve the Montessori method as Dr. Montessori developed and refined throughout her lifetime.
Today, AMI training centers and affiliated schools operate throughout the world, and the AMI diploma is widely-regarded as the gold standard in Montessori teacher education.
The other major Montessori organization in the United States is the American Montessori Society (AMS), founded in 1960 by a student of AMI Montessori. AMS has played an important role in expanding Montessori education throughout the United States. Because its headquarters are in New York City, it is particularly well known in the New York region.
Both organizations prepare dedicated Montessori educators but the primary difference is philosophical.
AMI places a strong emphasis on maintaining Montessori's original approach with as little variation as possible. AMS allows greater flexibility in adapting Montessori and incorporating additional educational methods.
Neither philosophy is inherently "right" or "wrong."
The important question for parents is whether a school faithfully follows the Montessori approach that research has shown to be effective.
Why AMI Teacher Training Is Different
People often ask what it really means when a teacher is "AMI-trained."
The answer is much more than learning how to use Montessori materials.
An AMI diploma is widely regarded as one of the most rigorous credentials in early childhood education. Whether training to become an Aid to Life (ages 0-3), Primary (ages 3–6) or Elementary (ages 6–12) guide, trainees spend hundreds of hours studying child development, mastering every Montessori material, observing children, practicing lessons under supervision, and completing written and oral examinations before they can earn their diploma.
But the most transformative part of the training isn't the number of hours.
It's how you learn.
When I went to do my AMI training, we did not have textbooks. We were expected to write our own textbooks based on the Montessori lessons our trainers demonstrated for us. When you graduate, you leave with giant binders or manuals - all the writing created by the trainee themselves. Every theory lecture, every lesson, every presentation, every observation were verbally taught by our trainer, while the trainees (frantically!) wrote them down by hand. Montessori materials had to be replicated in drawings by hand. Even if you had poor artistic skills, you remember what you were trying to depict because you drew them! Today's trainees are often allowed to type their albums or include photographs, but the philosophy remains unchanged: you don't simply receive Montessori knowledge—you write down the lectures and lessons, then assemble the whole textbook yourself.
That process changed me - and everyone who went to training with me..
When you spend months observing children, practicing lessons, writing every concept in your own words, and organizing hundreds of pages into your own albums, you begin to understand Montessori in an entirely different way.
You're no longer memorizing information.
You're internalizing it.
I've often said that during AMI training:
You don't simply write the album—the album writes you. As you shape your album, it shapes your mind.
The process forces every trainee to slow down, think more deeply, observe more carefully, and continually reflect on what they are learning. Over time, it becomes much more than professional training. It becomes a process of personal transformation. You leave not only with greater knowledge, but with greater patience, humility, observation, and respect for the incredible capabilities of children.
That is why every Lead Teacher at Ms. Lam Montessori completes authentic AMI training. Not simply because of the diploma, but because of the transformation teachers go through while earning it.
By the time they step into a classroom, they haven't just learned Montessori: they've been shaped by it.
What Does It Take to Become an AMI Montessori Teacher?
One of the reasons AMI-trained teachers are so highly respected around the world is the extraordinary depth of their preparation. Earning an AMI diploma is far more than completing a teacher certification course—it's an intensive professional education that transforms how educators observe children, understand development, and guide learning.
AMI Assistants to Infancy Diploma (Birth–3 Years)
The AMI Assistants to Infancy Diploma prepares educators to support children during the most extraordinary period of human development—from birth through age three. During these years, children develop movement, language, independence, emotional security, and trust at an astonishing pace. AMI training helps teachers understand not only whatyoung children need, but why each experience during these formative years matters.
The program includes approximately 650 hours of professional preparation, including:
More than 400 hours of classroom lectures, demonstrations, and supervised practice
250 hours of observation of children from birth to three years of age in a variety of settings
To earn the AMI Diploma, trainees must successfully complete:
Original Montessori albums written in their own words
Required reading and seminars
Observation reports
Practice teaching as scheduled
A minimum of 90% attendance in lectures, demonstrations, discussions, and seminars
Comprehensive written and oral examinations
AMI Primary Diploma (Ages 3–6)
The AMI Primary Diploma includes approximately 710 hours of formal preparation, including:
More than 400 hours of classroom lectures and demonstrations
140 hours of supervised practice with Montessori materials
170 hours of classroom observation and teaching practicum in authentic Montessori environments
To graduate, every trainee must successfully complete:
Original Montessori albums written in their own words
Required reading and seminars
Montessori material making
Supervised practice with every Montessori material
Classroom observations and observation reports
Teaching practicum
A minimum of 90% attendance
Comprehensive written and oral examinations
Rather than studying from a textbook, AMI trainees create their own. Their albums become lifelong professional reference manuals and represent hundreds of hours of careful study, observation, and reflection. It is one of the defining characteristics of AMI teacher education.
AMI Elementary Diploma (Ages 6–12)
The AMI Elementary Diploma prepares teachers to guide children through the elementary years—a period characterized by imagination, reasoning, collaboration, and intellectual exploration.
The program includes approximately 790 hours of professional preparation, including:
More than 440 hours of classroom lectures and demonstrations
140 hours of supervised practice with Montessori materials
210 hours of classroom observation and vocational placement in Montessori schools
Applicants must already hold an AMI Primary Diploma or complete the AMI Foundation Course before beginning the Elementary training.
Graduation requires successful completion of:
Original Montessori albums for every curriculum area
Required reading and seminars
Supervised practice with Montessori materials
Observation reports
Practice teaching and teaching reports
A minimum of 90% attendance
Comprehensive written and oral examinations
Only after all academic, practical, and examination requirements have been successfully completed is the internationally recognized AMI Diploma awarded.
What was Ms. Lam’s AMI Montessori Training like?
My mother, Ms. Lam, completed her AMI training in 1984—long before laptops, digital cameras, or even personal computers were part of everyday life.
Every Montessori album was written entirely by hand. Every material was carefully illustrated by hand. There was no copying and pasting, no printing, and no downloading lecture notes. Every page represented hours of observation, study, and reflection.
When she flew home to Taiwan after completing her training, she checked all of her luggage—but not her albums. Despite their incredible weight, she carried every one of them onto the plane by hand. She often says she could have replaced all of her belongings, but she could never replace those albums.
They weren't just notebooks.
They represented months of intensive work, countless hours of observation, and a profound transformation in how she understood children. Those albums became the foundation upon which she built Ms. Lam Montessori over 40 years ago, and they continue to influence the way we educate children today.
What was Stephanie’s AMI Montessori Training like?
I completed 3 levels of AMI Montessori training:
Assistants to Infancy (Birth–3) in 2012
Primary (Ages 3–6) in 2014
Elementary (Ages 6–12) in 2018
Experiencing every level of AMI training gave me a deep appreciation for the remarkable continuity of Montessori education—from a baby's first movements to an elementary child's growing imagination and reasoning.
One of the biggest surprises was the rigor. My own Ivy League education was about the same in terms of rigor, perhaps even a little less than AMI training!
The second biggest surprise was the fact that we weren't given textbooks - we had to create our own! Every lesson, every theory lecture, every material presentation, and every observation became part of albums that we wrote in our own words. By the end of the course, we didn't simply have notes—we had created our own comprehensive Montessori manuals that would guide us throughout our careers.
Looking back, I believe this was one of the most powerful aspects of the training. Writing every lesson in your own words forces you to understand Montessori at a much deeper level than simply reading a book. It requires you to think critically, connect ideas, and truly internalize the philosophy behind every lesson.
I've often said, during AMI training:
You don't simply write the album—the album writes you. As you shape your album, it shapes your own mind.
That experience continues to influence every classroom I've built, every teacher I've mentored, and every decision we've made at Ms. Lam Montessori. It is one of the main reasons we require every Lead Teacher to complete authentic AMI training. We believe that the quality of a Montessori education begins with the preparation of the adult who guides the child.
Why Fidelity to the Method Matters
Research supporting Montessori education has become increasingly compelling.
A landmark 2025 randomized controlled trial published in the Proceedings of the National Academy of Sciences, one of the world’s most respected journals, found that children in Montessori classrooms demonstrated stronger reading skills, executive function, memory, and social understanding by kindergarten.
Other long-term studies have shown similar benefits.
But there is an important detail that often gets overlooked.
These studies were conducted in high-fidelity AMI Montessori classrooms.
That means classrooms with:
Highly trained Montessori teachers
Authentic Montessori materials
Three-year mixed-age classrooms
Long, uninterrupted work periods
Child-led learning within a carefully prepared environment
In other words, researchers weren't studying schools that simply used Montessori materials. They were studying schools that faithfully implemented the Montessori method.
Montessori-Inspired vs. Authentic Montessori
Today, you'll often hear schools describe themselves as "Montessori-inspired." There's nothing inherently wrong with that. In fact, many Montessori-inspired schools are warm, thoughtful places where children are well cared for.
The important thing for parents to understand is that Montessori-inspired and authentic Montessori are not the same thing.
A Montessori-inspired school may borrow certain Montessori materials, encourage child independence, or incorporate aspects of Montessori philosophy while also using teacher-directed lessons, worksheets, reward systems, or single-age classrooms. These schools intentionally blend Montessori with other educational approaches.
An authentic Montessori school follows the method as an integrated system. The materials, the prepared environment, the role of the teacher, the three-year mixed-age classroom, the uninterrupted work period, and the carefully sequenced lessons all work together. Each element supports the others, creating an environment that allows children to develop concentration, independence, self-discipline, and a genuine love of learning.
Calling a school "Montessori-inspired" is a little like saying a restaurant is "French-inspired." It may borrow ideas, ingredients, or techniques from French cuisine, but that doesn't necessarily mean you're eating traditional French cooking. The same is true in education. A Montessori-inspired school may incorporate elements of Montessori while combining them with other philosophies. An authentic Montessori school follows the Montessori method as a complete, integrated system.
That is why, when choosing a Montessori school, it's worth asking not just whether a school uses Montessori materials, but whether it follows the Montessori method with fidelity.
What to Look For When Visiting a Montessori School
If you're touring Montessori schools, here are a few questions worth asking.
Who trained the teachers?
Ask whether the Lead Teachers hold AMI or AMS diplomas from accredited Montessori training programs.
Are the classrooms mixed-age?
Authentic Montessori classrooms intentionally span three years because children learn from one another as much as they learn from adults.
Is there an uninterrupted work period?
Children should have a long block of uninterrupted time (minimum 2 hours for toddlers and 3 hours for Primary) to choose meaningful work, concentrate deeply, and progress at their own pace.
Are rewards used?
Sticker charts, prizes, and behavior systems are inconsistent with Montessori's emphasis on intrinsic motivation.
Is the environment prepared for independence?
Children should be moving independently, making choices, caring for their environment, and taking responsibility appropriate to their developmental stage.
How Ms. Lam Montessori Applies AMI Standards
For more than forty years, Ms. Lam Montessori has remained committed to authentic AMI Montessori education across our campuses in Taiwan and Brooklyn.
Our classrooms follow authentic Montessori principles, including:
AMI Montessori-trained teachers
Three-year mixed-age classrooms
Uninterrupted morning work periods
Authentic Montessori materials
Individualized lessons
Observation-based teaching
Carefully prepared environments
On top of this authentic Montessori foundation, children are immersed in Mandarin Chinese throughout the day, giving them the opportunity to develop both cognitive flexibility and bilingual fluency during the years when language acquisition is most natural.
If you'd like to experience an authentic AMI Montessori classroom for yourself, we invite you to visit one of our Brooklyn campuses.
Frequently Asked Questions
What does AMI stand for?
AMI stands for Association Montessori Internationale, the organization founded by Dr. Maria Montessori in 1929 to preserve and promote the Montessori method throughout the world.
Is AMI better than AMS?
Rather than asking which organization is "better," it's more helpful to understand their different approaches.
AMI emphasizes preserving Montessori's original method with a high degree of fidelity. AMS allows greater flexibility in adapting Montessori within modern educational settings. The founder of AMS was a student of AMI Montessori, who decided to incorporate different educational methods than those of strict AMI.
Both organizations prepare dedicated educators. The important question is whether a school faithfully implements Montessori principles in everyday classroom practice.
Why is AMI teacher training considered so rigorous?
AMI teacher training typically requires nine to twelve months of intensive study, including classroom lectures, hundreds of hours of supervised practice, child observation, teaching practicum, album preparation, and written and oral examinations.
The training is internationally recognized for its depth and rigor.
The Bottom Line
When parents ask whether AMI is "better," they're often asking the wrong question.
A better question is:
How faithfully does a school implement Montessori?
The quality of a Montessori education isn't determined by beautiful materials alone. It comes from the preparation of the teacher, the carefully designed environment, and a deep respect for how children naturally learn.
For more than forty years, that commitment has guided every classroom we have built at Ms. Lam Montessori.
Because we believe children deserve nothing less.