Catechism of the Catholic Church §1588 — excerpt
With regard to deacons, "strengthened by sacramental grace they are dedicated to the People of God, in conjunction with the bishop and his body of priests, in the service (diakonia) of the liturgy, of the Gospel, and of works of charity."
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: LG 29