64 After this appeal to the clergy, We extend Our paternal invitation to Our beloved sons among the laity who are doing battle in the ranks of Catholic Action. On another occasion We have called this movement so dear to Our heart "a particularly providential assistance" in the work of the Church during these troublous times. Catholic Action is in effect a social apostolate also, inasmuch as its object is to spread the Kingdom of Jesus Christ not only among individuals, but also in families and in society. It must, therefore, make it a chief aim to train its members with special care and to prepare them to fight the battles of the Lord. This task of formation, now more urgent and indispensable than ever, which must always precede direct action in the field, will assuredly be served by study-circles, conferences, lecture-courses and the various other activities undertaken with a view to making known the Christian solution of the social problem.
Source: Divini Redemptoris (Vatican.va)