Anna Freud was a strong supporter of Maria Montessori, and the Montessori approach to education. Her father also corresponded with Montessori, and professed his respect.
Anna Freud writes, in the preface to Maria Montessori: A Biography, that as a contemporary, she is impressed that "the most important elements of the Montessori method" entered into modern discourse "in one form or another" and became indispensable components in the education of small children...". She lists both sense perception studies and metaphysics as the primary elements that contributed to the success of Maria Montessori.
In a letter of correspondence, Freud himself states, "I am in deep sympathy with your humanitarian and understanding endeavors, and my daughter, who is an analytic pedagogue, considers herself one of your disciples."