She is a longtime Chicana activist icon from San Antonio. Raised by a single mother, she earned a Bachelor of Arts degree in Spanish from Our Lady of the Lake College, and a master’s degree in environmental management from UTSA; in 2017, Our Lady of the Lake University conferred an honorary doctoral degree on her.
Already active in political organizing during her college days, she ran for the San Antonio City Council in 1971 under the Committee for Barrio Betterment. She also served as county chair of the Raza Unida Party, a party that she helped found, in Bexar county. Castro retired as interim Dean of Student Affairs and Director of the Center for Academic Transitions at Palo Alto College but has remained active in social justice activism in San Antonio.