In what could be a defining moment for his papacy, more than 100 top Catholic bishops from around the world will travel to the Vatican this week for a conference aimed at dealing with the issue of clergy sex abuse.

Pope Francis is the first church leader to convene such a meeting to discuss the issue. And after a year in which high-ranking church officials resigned in scandal, the conference that opens Thursday could present an opportunity for him to dispel criticism that he has responded sluggishly as the crisis continued worldwide.

But should his four-day event fail to deliver, the pope risks cementing the impression among detractors that he remains resistant to meaningful change.

Sex-abuse victims are expected to set up shop outside the Vatican as the prelates meet privately.

“They know that this is a very high-stakes meeting,” said Massimo Faggioli, a theologian and scholar of church history at Villanova University.

“The attention here in Rome is already similar to what you’d see for a papal conclave.”

As if to signal his seriousness, Francis this weekend took his most meaningful step to date by defrocking Theodore McCarrick, a former cardinal and archbishop of Washington, D.C., after the church found him guilty of sexually abusing minors and adult seminarians.