23 Whether the lay apostolate is exercised by the faithful as individuals or as members of organizations, it should be incorporated into the apostolate of the whole Church according to a right system of relationships. Indeed, union with those whom the Holy Spirit has assigned to rule His Church (cf. Acts 20:28) is an essential element of the Christian apostolate. No less necessary is cooperation among various projects of the apostolate which must be suitably directed by the hierarchy. Indeed, the spirit of unity should be promoted in order that fraternal charity may be resplendent in the whole apostolate of the Church, common goals may be attained, and destructive rivalries avoided. For this there is need for mutual esteem among all the forms of the apostolate in the Church and, with due respect for the particular character of each organization, proper coordination. This is most fitting since a particular activity in the Church requires harmony and apostolic cooperation on the part of both branches of the clergy, the Religious, and the laity.
Source: Apostolicam Actuositatem (Vatican.va)