 In 1929, due to the increasing numbers of Puerto Ricans settling in southwest Harlem, Belpré was transferred to a branch of the NYPL at 115th Street.She quickly became an active advocate for the Spanish-speaking community by instituting bilingual story hours, buying Spanish language books, and implementing programs based on traditional holidays like the celebration of Three Kings Day.In her outreach efforts, she attended meetings of civic organizations such as the Porto Rican Brotherhood of America and "La Liga Puertorriqueña e Hispana".