The Holy Father was speaking in an impoverished area of Naples where more than half of young people are jobless and many will end up joining the Mafia.
Francis said young people must hold onto hope and not be taken into a life of crime by local 'dons'.
Speaking to the residents of Scampia, a rundown neighbourhood dominated by mobsters, the Pope bemoaned the unemployment level.
He also called on the Mafia to abandon its criminal ways and turn to God.
Young people must resist the "easy earnings or dishonest income" of crime, he said.