Maria Montessori was born in Chiaravalle, in the province of Ancona, Italy, in 1870. In 1896, she graduated from the University of Rome with top honours to become the first female physician in Italy. After graduating, she was appointed as an assistant in the San Giovanni Hospital, working with women and children and in 1897 when became a voluntary assistant at the psychiatric clinic of the University of Rome.

For two years Montessori helped disturbed and handicapped children learn and develop, basing her methods on the teachings of two prominent French physicians, Jean Itard and Edouard Sequin. She found that the children progressed so quickly that, when she signed them up for ordinary school examinations, they passed without difficulty. Rather than being impressed by the accomplishment, it led her to question the schools who gave examinations that could be passed by seriously disadvantaged children, after only two years of using her improvised methods.

In 1901 she gave up her work at the Orthophrenic School to further her studies in anthropology, psychology and educational philosophy at the University of Rome. Around this time she also gave birth to an illegitmate child, Mario Montessori. The father was a colleague at the Clinic, Dr Montesano. Mario was brough up by his foster parents, but later adopted by his mother. In 1904, she was made a professor of anthropology at the University of Rome.

In 1906 she gave up both her university chair and her medical practice to work with a group of sixty young children of working parents in the San Lorenzo district of Rome. The school opened in January 1907 a large tenement house in San Lorenso, was for children aged three to six years old. She called it 'Casa dei Bambini'. In the following two years, other children's houses were founded and Montessori was able to apply her methods to normal children.

Montessori was able to show that children were able to become independent learners when taught by her methods. In 1909 her book, The Method of Scientific Pedagogy as Applied to Infant Education and the Children's House, was published. The book was later retitled to The Discovery of the Child.

At this time Maria Montessori spent all her time training teachers, writing and giving lectures. She made her first visit to the United States in 1913, the same year that Alexander Graham Bell and his wife Mabel founded the Montessori Educational Association at their Washington, DC, home. Among her other strong American supporters were Thomas Edison and Helen Keller.

In 1915, she attracted world attention with her "glass house" schoolroom exhibit at the Panama-Pacific International Exhibition in San Francisco. On this second U.S. visit, she also conducted a teacher training course and addressed the annual conventions of both the National Education Association and the International Kindergarten Union. The committee that brought her to San Francisco included Margaret Wilson, daughter of U.S. President Woodrow Wilson.

In 1917 Montessori based herself in Barcelona, Spain where a Seminari Laboratori di Pedagogia had been created for her. In 1919, she began a series of teacher training courses in London. In 1922, she was appointed a government inspector of schools in her native Italy, but because of her opposition to Mussolini's fascism, she was forced to leave Italy in 1934. She traveled to Barcelona, Spain, and was rescued there by a British cruiser in 1936, during the Spanish Civil War. She opened the Montessori Training Centre in Laren, Netherlands, in 1938, and founded a series of teacher training courses in India in 1939.

In 1940, when India entered World War II, she and her son, Mario Montessori, were interned as enemy aliens, but she was still permitted to conduct training courses. Later, she founded the Montessori Centre in London (1947). She was nominated for the Nobel Peace Prize three times — in 1949, 1950, and 1951.

Maria Montessori died in Noordwijk, Holland, in 1952, but her work lives on through the Association Montessori Internationale (AMI), the organization she founded in Amsterdam, Netherlands, in 1929 to carry on her work.