Don Mon was born in Mayagüez (at the Rio Cañas Arriba ""barrio"" in the outskirts of the city, close to the place Eugenio María de Hostos was born) in 1899, and lived in the working class Barcelona barrio of the city proper. He was a janitor and handyman at the nearby University of Puerto Rico - Mayagüez for more than 40 years, and was well loved by the campus community. Known as ""'Rate"" by his closest friends, Don Mon gained a strong reputation as a composer of plenas, a musical genre considered the "musical newspaper of the barrio". He assembled impromptu plena jams in the neighborhood, which were so widely known that they were preserved for posterity in the documentary film (1956) by Amilcar Tirado (Don Mon appears at the last segment, improvising lyrics). Curiously enough, at the time don Mon was illiterate and had no formal musical training.