Alegría was born in Estelí, Nicaragua, to a Nicaraguan father, Daniel Alegría, and a Salvadoran mother, Ana María Vides. Her cousin was activist Leonel Gómez Vides. When Claribel was nine months old, her father was sent into exile for protesting human rights violations occurring during the United States occupation of Nicaragua; as a result, Claribel grew up in Santa Ana, a city in western El Salvador, where her mother came from. Claribel Alegría considered herself to be Nicaraguan-Salvadorean. Although she was too young to read or write, she began composing poetry at the age of six and dictated them to her mother, who would write them down. Alegría consistently cited Rainer Maria Rilke's "Letters to a Young Poet" as the impetus for becoming a poet. At the age of seventeen, she published her first poems in Repertorio Americano, a Central American cultural supplement. Soon after, Mexican educator José Vasconcelos arranged for Alegría to attend finishing school in Hammond, Louisiana. In 1943, she moved to the United States and in 1948 received a B.A. in Philosophy and Letters from George Washington University. Alegría was committed to nonviolent resistance. She had a close association with the Sandinista National Liberation Front (FSLN), which overthrew Anastasio Somoza Debayle and took control of the Nicaraguan government in 1979. Alegría returned to Nicaragua in 1985 to aid in the reconstruction of Nicaragua.