This volume contains twelve complete and two excerpted documents which together constitute the most authoritative and most recent social teaching of the Roman Catholic Church. All but four of them are encyclical letters. Of these four, two are statements prepared by bishops meeting in Rome. Of the remaining two, one is called an 'Apostolic Letter', the other an 'Apostolic Exhortation'. Both were written by Pope Paul VI, whose last formal encyclical was Humanae Vitae, published in 1968: after that he appears to have chosen forms of communication other than encyclicals.