Cleaners and cooks. Doctors and nurses. Even drivers and elevator operators. The support staff for the cardinals who will elect the successor to Pope Francis took an oath of secrecy Monday ahead of the conclave that’s starting on Wednesday.

Workers and clerics assisting the dozens of Catholic cardinals set to gather Wednesday to begin voting on the next pope had to swear to never reveal anything about the proceedings or else risk the Church’s gravest punishment: religious banishment. The employees took their oaths in the Papal Chapel.

The oath-taking is being held in the Pauline Chapel at the Vatican for all those assigned to the upcoming conclave. They include clerics in support roles, including confessors speaking various languages. The cardinals themselves will take their oath on Wednesday in the Sistine Chapel, before they cast their first ballots.