Leticia del Rosario (full name: Leticia Rafaela del Rosario Mejía) was born in Yauco, Puerto Rico on June 4, 1914. Her parents were Carlos Antonio del Rosario Rodríguez, a pharmacist, and Juana Josefa Mejía Rodríguez. She was the youngest of eight children. When she was 3 years old, the family moved to San Juan, Puerto Rico, where she completed her primary and secondary studies at Colegio Puertorriqueño de Niñas, a secular private school for women.