Feast that celebrates "the one and equal glory" of Father, Son, and Holy Spirit, "in Trinity of Persons and in Unity of Being" (BCP, p. 380). It is celebrated on the first Sunday after Pentecost. Trinity Sunday is one of the seven principal feasts of the church year (BCP, p. 15). The proper readings and collect for Trinity Sunday are used only on the feast, not on the weekdays following. The numbered proper which corresponds most closely to the date of Trinity Sunday is used (BCP, p. 228). The BCP also provides the proper "Of the Holy Trinity" for optional use at other times, subject to the rules of the calendar of the church year (see BCP, pp. 251, 927). The Hymnal 1982 presents ten hymns in a section on The Holy Trinity (Hymns 362-371), including "Holy, holy, holy! Lord God Almighty!" (Hymn 362), "Come, thou almighty King" (Hymn 365), and "Holy Father, great Creator" (Hymn 368).
Celebration of Trinity Sunday was approved for the western church by Pope John XXII in 1334. This feast is associated with Thomas Becket (c. 1118-1170), who was consecrated bishop on Trinity Sunday, 1162. His martyrdom may have influenced the popularity of the feast in England and the custom of naming the remaining Sundays of the church year "Sundays after Trinity." The Sarum Missal and editions of the Prayer Book through the 1928 BCP named these Sundays the Sundays after Trinity. The 1979 BCP identifies this portion of the church year as the season after Pentecost, and names these Sundays the Sundays after Pentecost (see BCP, p. 32).