20 Many decades ago the laity in many nations began to dedicate themselves increasingly to the apostolate. They grouped themselves into various kinds of activities and societies which, while maintaining a closer union with the hierarchy, pursued and continue to pursue goals which are properly apostolic. Of these associations, or even among similar and older institutions, those are specially noteworthy which followed different methods of operation and yet produced excellent results for Christ's kingdom. These societies were deservedly recommended and promoted by the popes and many bishops, from whom they received the title of "Catholic Action," and were often described as the collaboration of the laity in the apostolate of the hierarchy. Whether these forms of the apostolate have the name of "Catholic Action" or some other title, they exercise an apostolate of great value for our times and consist in the combination and simultaneous possession of the following characteristics: a) The immediate aim of organizations of this kind is the Church's apostolic aim, that is, the evangelization and sanctification of men and the formation of a Christian conscience among them so that they can infuse the spirit of the Gospel into various communities and departments of life. b ) Cooperating with the hierarchy in their own way, the laity contribute the benefit of their experience to, and assume responsibility for the direction of these organizations, the consideration of the conditions in which the pastoral activity of the Church is to be conducted, and the elaboration and execution of the plan of things to be done. c) The laity act together in the manner of an organic body so that the community of the Church is more fittingly symbolized and the apostolate rendered more effective. d) Whether they offer themselves spontaneously or are invited to action and direct cooperation with the apostolate of the hierarchy, the laity function under the higher direction of the hierarchy itself, and the latter can sanction this cooperation by an explicit mandate. Organizations in which, in the opinion of the hierarchy, the ensemble of these characteristics is realized, must be considered to be Catholic Action even though they take on various forms and titles because of the needs of different regions and peoples. The most holy council earnestly recommends these associations, which surely answer the needs of the apostolate of the Church among many peoples and countries, and invites the clergy and laity working in them to develop the above-mentioned characteristics to an ever greater degree and to cooperate at all times with all other forms of the apostolate in a fraternal manner in the Church.
Source: Apostolicam Actuositatem (Vatican.va)