A society, whether clerical or lay, whose members profess the evangelical counsels in the world. Their purpose is to enable the members to attain Christian perfection and to exercise a full apostolate. They are distinguished in ecclesiastical law from other common associations of the faithful. They were first approved by Pope Pius XII on February 2, 1947, in his constitution Provida Mater, which still contains the guiding norms for their directions. Secular institutes differ from formal religious institutes or societies of common life because, while their members take vows or promises, these are not technically the public vows of religion, and the members do not live a common life. They are, however, states of Christian perfection, whose apostolate is in the world. The members are to work for the extension of Christ's kingdom in places and circumstances corresponding to people in the secular world.