The archivist Pepita Callao showed her activism from a young age, forming part of the founding nucleus of the Spanish University Federation (FUE). Along with Carmen Caamaño and other students, she was one of the first five women arrested in the feminist movement in Spain in 1929.
In 1931, she entered the Body of Archivists, Librarians, and Archaeologists by competitive examination and was assigned to the Archive of the Palencia Tax Office. At the end of that year, she was transferred by competitive examination to the Archive of the Crown of Aragon.
In 1933, she married the Mallorcan engineer and politician Antoni María Sbert .
During the Civil War she created, with Jordi Rubio i Balaguer, the Servei de Biblioteques del Front of the Generalitat de Catalunya , at the same time her husband was Minister of Culture. After the fall of Barcelona, she went into exile in France. Meanwhile, in Spain, she was purged and dismissed from the Body of Archivists by order of July 1939.
Later, the family left for Mexico, arriving on board the Nyassa in 1942. There she collaborated with the JARE and founded the Union of Spanish Women (UME).