Pope John XXIII issued two major encyclicals, Mater et Magistra and Pacem in Terris, in which he called the faithful and people of good will to work toward the common good. Inside is a collection of links to his writings.
Ad Petri Cathedram (To the Chair of Peter), June 29, 1959
Mater et Magistra (On Christianity and Social Progress), May 15, 1961.
Aeterna Dei Sapientia (On Commemorating the Fifteenth Centennial of the Death of Pope Saint Leo I: The See of Peter as the Center of Christian Unity), November 10, 1961.
Pacem in Terris (Peace on Earth) April 11, 1963.
John XXIII on Human Rights and Duties, April 11, 1963
John XXIII on Social Rights, April 11, 1963
John XXIII on Women's Rights, April 11, 1963
John XXIII on Democracy, April 11, 1963
John XXIII on Nuclear Disarmament, April 11, 1963
John XXIII on Unity Among Christians, November 10, 1961