She studied at the teacher's colleges "Maria Stagnero of Munar" and "R. Joaquin Sanchez" earning a degree for teaching primary school.
[1] During her university studies, Castro joined several militant campus organizations and at political rallies met Raúl Sendic, who became one of the leaders of the Tupamaros guerrillas.
She also taught teacher training at the Normal Institutes of Montevideo and the IPA, retiring from the National Administration of Public Education (ANEP) in 1998.
From 1997 to 1999 she worked with then-deputy José Mujica campaigning and until the end of 1999 she sold books, fabrics, crafts, and other items to supplement her income.
In addition, she worked on the Special Committee on Gender and Equity for Health Education and was a participant in the Bicameral Women's Caucus.
Several other deputies, including Margarita Percovich, Diana Saravia Elms, Lucía Topolansky, and Daisy Tourné were instrumental in developing the organization.