Watch a video for World Mission Sunday (below), with a special message by Archbishop Nelson Pérez, on the annual observance of the Catholic Church’s global mission to encounter all peoples and build the church throughout the world. A Mass for World Mission Sunday, Oct. 18, will be celebrated at the Cathedral Basilica of SS. Peter and Paul, Philadelphia, at 11 a.m. Read more about the Pontifical Mission Societies of the Archdiocese of Philadelphia, and read a reflection on World Mission Sunday here.