El Imparcial, founded in 1918, was "an anti-Popular, pro-Independence tabloid"[4] in Puerto Rico.

[7] The paper Valdivieso bought that year for $2,000 at an auction was described as a "floundering literary periodical" in his obituary; under his leadership it became Puerto Rico's second largest newspaper (after El Mundo).

[8] Valdivieso, who had headed the nationalist party prior to acquiring the paper, penned editorials arguing for Puerto Rican independence.

In the late 1960s the family brought in new management, which made a number of changes, including softening the pro-independence stance.

Other contributors were Carmen Mirabal, Aida Zorrilla, Miguel Angel Yumet, Luis Colón, Victor M. Padilla and Millie Cappalli Arango.