Falcón and the essayist Moquegua José Carlos Mariátegui co-founded the newspaper La Razón (Reason).

Mariátegui went to Italy and then travelled through Europe, with lengthy stays in France, Germany, Austria, Hungary and Czechoslovakia, where he became imbued with Communist ideology.

Mariátegui then joined Falcón, Carlos Roe and Palmiro Machiavelo to found the first Peruvian Communist cell.

Falcón married Irene Lewy, who accompanied him under contract as correspondent by the daily La Voz (The Voice), a Spanish newspaper.

[2] Their son Mayo was born in London in May 1926 but was not registered at the Spanish consulate due to concerns with the dictatorship of Miguel Primo de Rivera.

[3] They published Historia Nueva (New History) and launched the party Izquierda Revolucionaria y Antiimperialista (IRYA: Anti-Imperialist Revolutionary Left).