Having completed her school studies between 1915 and 1918, majoring in mathematics, Castro began to attend literary salons in 1920, including those given by Veva de Lima. She would spend her Sundays at the home of the writer and poet, Branca de Gonta Colaço. A year later, she gave up attending a Polytechnic School and published her first book, Ante-manhã, containing verses written when she was between 15 and 18. Publication of this book, under the name of Maria Fernanda de Castro e Quadros, was a birthday present from family and friends. She was astonished to find that "my little book was not badly received". She then went on to win first prize in a competition to submit an original play. This was named Náufragos (Castaways) and was written in collaboration with her friend, Teresa Leitão de Barros. It had its first performance in 1924.
