Passion Sunday is a term formerly used to denote the fifth Sunday of Lent in the Christian liturgical calendar; since 1970, when the new church calendar approved by the Second Vatican Council went into effect, the term has been applied to the following Sunday, until then officially called Palm Sunday (the churches of the Anglican Confession adopted this new definition in 1976). The new meaning does not appear to have caught on with most laypersons within either polity, however, the majority of whom continue to use Palm Sunday to refer to the Sunday before Easter.

When the term Passion Sunday was applied to the fifth Sunday of Lent, it marked the start of a two-week sub-season often referred to as Passiontide (and the formal name for it in the Roman Catholic calendar was actually the First Sunday of the Passion). In Anglican churches that chose to follow the Sarum Rite, crimson vestments were pressed into service on this day - replacing either purple or the Lenten array (unbleached muslin cloth) - and vestments remained crimson through Holy Saturday. Since Passion Sunday has no longer been used to mean the fifth Sunday of Lent, crimson has been worn during the last week before Easter only. The entire week beginning with the fifth Sunday of Lent was often called Passion Week prior to the calendar reform, which officially transferred that term to the following week; yet, as in the case of Palm Sunday, most Roman Catholic and Protestant laity alike continue to refer to the last week before Easter by its original name, that of Holy Week.