CONCELEBRATION. — In a broad sense, concelebration is the assistance and active participation of ministers and the faithful in sacred functions; in a narrower sense, it is the union of sacred ministers alone, or of priests alone, in the function of a bishop, as was customary in antiquity, for example, in the administration of Baptism, Extreme Unction, and, as it continues today, in the laying on of hands for priestly ordination and the consecration of holy oils on Holy Thursday; in the proper sense, it is the active participation of several priests in the celebration of the Mass.
In the Latin Church, concelebration occurs in the consecration of a bishop and in priestly ordination. Concelebration is a very ancient institution. The *Liber Pontificalis* (I, 139, note 3) attributes it to Pope Zephyrinus (198–217). In Rome, priests celebrated together with the pope, while outside Rome they did so with the bishop. However, in the earliest Christian era, a true concelebration cannot be admitted, since the text of the prayers had not yet been fixed, but only the manner of celebrating (cf. Justin, *Apologia*, I, 65 and 67). Concelebration was rather a simple assistance in the presbyterium, as indeed the original text of the *Traditio Apostolica* of St. Hippolytus (223) indicates, though in a later redaction it becomes a true concelebration (E. Hauler, *Didascalia Apostolorum fragmenta Veronensia*, Leipzig 1900, p. 106). The Councils of Toledo I (400), Tarragona (516), and the province of Auvergne (585) order the assistance of priests and deacons at the divine sacrifice every day. Pope Innocent I (d. 417) writes to Bishop Decentius of Gubbio (PL 20, 476) that priests should have «the continuous duty of praying and sacrificing». A detailed description of concelebration is provided by the Roman Ordines III and IV (cf. ed. M. Andrieu, *Les Ordines romani du haut moyen âge*, II, Louvain 1948, pp. 131, 163), according to which the cardinal priests surrounded the pope at the altar and recited the canon together with him, including the consecratory words, while each had before him on a corporal three hosts to be consecrated. In Rome, concelebration took place on solemnities until the 13th century (Innocent III, *De sacrosancto altaris mysterio*, IV, 25: PL 21, 874; cf. *Ordo Romanus* XI [according to Mabillon], 20), after which it fell into disuse and was retained only for the ordination of bishops and priests. In the Gallican, Mozarabic, and Ambrosian rites, there is no evidence of a common consecration, but rather of concelebration.
Among the Eastern Churches, concelebration has been in use since the beginning, as the Councils of Neocaesarea (315) and Chalcedon (451) presuppose it, while the Constitutions of the Egyptian Church, the Canons of Hippolytus, the *Testamentum Domini*, and other ancient documents speak of II. St. Athanasius (*Apologia contra Arianos*, 8, 12) reproaches the priest Ischiras «because, although he was a priest himself, he never participated in the synaxis of other priests». Among the Greeks, concelebration came into greater use from the 15th century onward; in the Maronite rite, simultaneous concelebration has existed since the 17th century, which, among other Eastern rites, was first adopted by the Melkites in 1729, and later by others, so that it is now the common form among Easterners, who can perform it every day. While, however, the schismatics recite the consecratory words together with the rest of the canon, the Slavonic dissidents say them aloud, and the Hussites sing them. Concelebration vividly expresses the unity among sacred ministers in the highest and most sublime act of worship and their participation in the one priesthood of Christ.
