Born in Pontremoli, Chiarlo studied at the seminary in Lucca and the Pontifical University of St. Thomas Aquinas (Angelicum) in Rome before being ordained to the priesthood on 28 May 1904.
Born in Pontremoli, Chiarlo pursued theological studies at a seminary in Lucca and the renowned Pontifical University of St. Thomas Aquinas in Rome before being ordained to the priesthood on May 28, 1904.