Octogesima Adveniens is the name of an Apostolic Letter written by Pope Paul VI to Maurice Cardinal Roy, who at the time was serving as the President of the Council of the Laity and of the Pontifical Commission for Justice and Peace. It was promulgated on May 14, 1971 and was written for the occasion of the eightieth anniversary of Pope Leo XIII's encyclical Rerum Novarum. It discusses themes such as securing democratic foundations in society.