Passion Sunday is either the fifth or sixth Sunday of Lent.
Until 1959, the fifth Sunday of Lent was officially known as Passion Sunday. It marked the beginning of a two-week-long period known as Passiontide, which is still observed by various denominations in Protestantism and by some traditionalist Catholics. In 1960, Pope John XXIII's Code of Rubrics changed the name for that Sunday to "First Sunday of the Passion" bringing the name into harmony with the name that Pope Pius XII gave, five years earlier, to the sixth Sunday of Lent, "Second Sunday of the Passion or Palm Sunday".
Pope Paul VI's revision in 1969 removed a distinction that existed (although with overlap) between Lent and Passiontide, which began with the fifth Sunday of Lent. The distinction, explicit in the 1960 Code of Rubrics, predates it. He removed from the fifth Sunday of Lent the reference to the Passion.
Although Passiontide as a distinct liturgical season was thus abolished, the Roman Rite liturgy continues to bring the Passion of Christ to mind, from Monday of the fifth week of Lent onward, through the choice of hymns, the use on the weekdays of the fifth week of Lent of Preface I of the Passion of the Lord, with Preface II of the Passion of the Lord being used on the first three weekdays of Holy Week, and the authorization of the practice of covering crosses and images from the fifth Sunday of Lent onward, if the Conference of Bishops so decides. Where this practice is followed, crucifixes remain covered until the end of the Good Friday celebration of the Lord's Passion; statues remain covered until the beginning of the Easter Vigil.
The entrance antiphon of the Mass on the fifth Sunday of Lent begins with the word "Iudica" (older spelling, "Judica"). This provides another name for that Sunday: "Iudica Sunday" or "Judica Sunday", similar to the name "Laetare Sunday" for the fourth Sunday. Because of the custom of veiling crucifixes and statues in the church before Mass on the fifth Sunday of Lent, this Sunday was called Black Sunday in Germany, where the veils, which elsewhere were generally violet, were of black colour.