When her father was elected as the president of Chile on 4 September 1970, Beatriz became his closest advisor and collaborator, networking with elements of the Chilean and international Left. During Pinochet's coup, despite being pregnant, she stayed with her father in La Moneda Presidential Palace, leaving only when President Allende ordered all women and children to evacuate. She was forced into exile with her mother, sisters and daughter to Cuba. While in exile in Havana, she served as executive secretary of the Anti-Imperialist Solidarity Committee.