Montessori education is an educational approach developed by Italian physician and educator Maria Montessori based on her extensive research with "phrenasthenic" (mentally challenged) children and characterized by an emphasis on independence, freedom within limits, and respect for a child's natural psychological, physical, and social development. Although a range of practices exist under the name "Montessori", the Association Montessori Internationale (AMI) and the American Montessori Society (AMS) cite these elements as essential:
Maria Montessori began to develop her philosophy and methods in 1897, attending courses in pedagogy at the University of Rome and reading the educational theory of the previous two hundred years. In 1907, she opened her first classroom, the Casa dei Bambini, or Children's House, in a tenement building in Rome. From the beginning, Montessori based her work on her observations of children and experimentation with the environment, materials, and lessons available to them. She frequently referred to her work as "scientific pedagogy". In 1901, Maria Montessori met Alice and Leopold (Baron & Baroness) Franchetti of Città di Castello. They found many matching points between their work. Maria Montessori was invited to hold her first course for teachers and to set up a "Casa dei Bambini" at Villa Montesca, the home of the Franchetti's in Città di Castello. Maria Montessori decided to move to Città di Castello where she lived for 2 years and where she refined her methodology together with Alice Franchetti. In that period, she published her book in Città di Castello, as mentioned before. The Franchetti Barons financed the publication of the book and the methodology had the name "Method Franchetti-Montessori", until the fascists ordered the cancellation of the baroness’ name from the Method because she was Jewish. Alice Franchetti died in 1911 at 37.
Montessori education spread to the United States in 1931 and became widely known in educational and popular publications. However, conflict between Montessori and the American educational establishment, and especially the publication in 1914 of a critical booklet, The Montessori System Examined by influential education teacher William Heard Kilpatrick, limited the spread of her ideas, and they languished after 1914. Montessori education returned to the United States in 1960 and has since spread to thousands of schools there. Montessori continued to extend her work during her lifetime, developing a comprehensive model of psychological development from birth to age 24, as well as educational approaches for children ages 0 to 3, 3 to 6, and 6 to 12. She wrote and lectured about ages 12 to 18 and beyond, but these programs were not developed during her lifetime.