Francis celebrated an emotional penitential liturgy inside Panama's main youth lock-up, the Las Garzas de Pacora detention centre.
In a twist, he was also hearing the inmates' confessions inside confessionals made by the detainees.
It is all part of Francis's belief that prisoners deserve the same dignity as everyone else - as well as hope.
"There are no words to describe the freedom I feel in this moment," one of the inmates, Luis Oscar Martinez, told the Pope at the start of the service.
In his homily, Francis recalled that society tends to label people good and bad, the righteous and the sinners, when it should spend its time creating opportunities for them to change.
"This attitude spoils everything, because it erects an invisible wall that makes people think that, if we marginalise, separate and isolate others, all our problems will magically be solved," he said, again making reference to the walls that seek to divide people rather than unite them.
"When a society or community allows this, and does nothing more than complain and backbite, it enters into a vicious circle of division, blame and condemnation."
Francis has made a tradition of visiting prisoners during his foreign visits, and has long made prison ministry part of his vocation to minister to the most marginal in society.
Last year, he changed church teaching on the death penalty, saying it was inadmissible in all cases.
The change was in keeping with his belief that prisoners can always change and deserve chances for rehabilitation so they can re-enter society after serving their terms.
In a sign of that need for inclusion, many of the inmates were wearing the World Youth Day white T-shirts that thousands of pilgrims were sporting around Panama City.
"A society is fruitful when it is able to generate processes of inclusion and integration, of caring and trying to create opportunities and alternatives that can offer new possibilities to the young, to build a future through community, education and employment," Francis said.
Las Garzas houses more than 150 inmates, some of whom are serving time for murder.
The facility, considered a model jail, opened a year after five minors died in a fire at another prison in Panama City in 2011.
Nine people including administrators and police were convicted of homicide or negligence in what was the worst tragedy for the country's youth prison system.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.
