Catechism of the Catholic Church §927 — excerpt
All religious, whether exempt or not, take their place among the collaborators of the diocesan bishop in his pastoral duty. From the outset of the work of evangelization, the missionary "planting" and expansion of the Church require the presence of the religious life in all its forms.
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: CD 33-35 · CIC, can. 591 · AG 18 · 40 · John Paul II, RMiss 69