This paper considers the process of becoming an international public intellectual, taking the case of Maria Montessori (1870-1952), the Italian physician who became an authority on education and, unusually for a woman, a public intellectual. The focus is on her experience from the age of 12 which contributed to her emergence on the international stage. In 1909, she set out her child-centred, resource-based pedagogy in "Il Metodo della Pedagogia Scientifica applicato all'educazione infantile nelle Case dei Bambini" (Montessori, 1909). This translates as 'The Method of Scientific Pedagogy applied to infant education in the Children's Houses'. In 1912, the English translation was entitled The Montessori Method, as her name was already known. The following year in the United States, her public lectures attracted audiences of thousands, receiving wide press coverage. Montessori's engagement with a wide public through her lectures and training courses is evident in her biographies (Gilsoul and Poussin, 2020; Honneger Fresco, 2018; Kramer, 1976). Recent scholarship highlights the importance of her technical skills, rather than her charisma. This article will explore Montessori's development in courage and confidence as a public speaker.