Celebrated every year on the second-to-last Sunday of October, World Mission Sunday is the day when Catholics around the world unite to support the missionary work of the Church. Established by Pope Pius XI in 1926, it remains the only annual global collection that directly supports mission territories where the Church is young, struggling, or persecuted. On this day, every parish, in every diocese, in every country, joins in prayer and giving to ensure that missionaries can continue their vital work—building churches, forming priests, supporting catechists, and serving communities in need.

This year, World Mission Sunday is October 18, 2026.

“One in Christ, united in mission” is the theme of this year's World Mission Sunday, which will commemorate the 100th anniversary of its establishment by Pius XI at the suggestion of the Pontifical Society for the Propagation of the Faith.

This theme highlights the unity of believers in faith, founded on the unity of Christ with the Father, and the consequent common mission of evangelization.