After her second marriage Lamas started to write for other newspapers, such as
O Século, and
A Capital, as well as publishing poems (
Os Humildes, 1923), serials, novels (
Caminho Luminoso,
Para Além do Amor,
Ilha Verde), and stories for children. Her works for women were more political and focused on improvements to women's rights. In 1928, she was invited to direct the supplement,
Modas & Bordados of
O Século, at the invitation of the writer José Maria
Ferreira de Castro. Her work on this magazine, which lasted almost two decades, quickly led to the supplement's losses being reversed, as a result of her approach of writing "woman to woman" and questioning the traditional and conservative standards of women in Portuguese society. In 1936, she also created a supplement,
Joaninha, for girls. She became friends with other female authors in Portugal, such as
Branca de Gonta Colaço. In 1936 she joined the
National Council of Portuguese Women (CNMP), chaired at that time by feminist activist
Adelaide Cabete. She began a relationship with Ferreira de Castro, often referred to by historians as being an "amitié amoureuse". They exchanged numerous letters, postcards and telegrams reporting on daily life, travel, thoughts, sadness, dreams and compliments about each other's literary work, ending only in 1973, the year before his death. Apparently, they planned for these to be published after their deaths. In 1930, she created, together with the CNMP and
O Século, an "Exhibition of Female Work, ancient and modern of a literary, artistic and scientific character", which intended to give visibility to women's work from all of Portugal. It generated much media attention and also raised her visibility with the CNMP, which elected her President for Education in 1937 and Literature in 1939. She was made an Officer of the
Order of Santiago () on 7 February 1934, for her work on behalf of women. A year later, she joined the
Associação Feminina Portuguesa para a Paz (Portuguese Women's Peace Association - AFPP), where she got to know a fellow feminist and anti-government activist,
Virgínia Moura. From this time, she started to sign her work as Maria Lamas, having previously used pseudonyms such as "Serrana d'Ayre", "Rosa Silvestre", "Vagna Ina" and "Armia", the last mainly being used in the magazine
Alma feminina, the official means of communication of the CNMP. ==After the Carnation Revolution==