World Youth Day (commonly abbreviated to WYD) is a youth-oriented Catholic Church event. While the event itself celebrates the Catholic faith, the invitation to attend extends to all youth, regardless of religious convictions.^[1] World Youth Day is not associated with International Youth Day or any of the international observance days.

World Youth Day was initiated by Blessed Pope John Paul II in 1985. It is celebrated diocesan level annually, and at a week-long international level every two to three years at different locations. The international level events attract hundreds of thousands of youth from almost every country on the planet. It is a major part of the upsurge in Catholic Youth Work in some countries over recent years; for example, the Director of Catholic Youth Services for England and Wales has said of the event that it would have far-reaching effects, not restricted to those who attended.^[2]

The Patron Saint of World Youth Days is Blessed Mother Teresa of Calcutta. Since his beatification, Pope John Paul II, who started the event, has become its co-patron.