15 May – Pope Pius XI publishes the minor encyclical Quadragesimo anno ("Fortieth year"),[4] which restates the points of the encyclical Rerum novarum of Pope Leo XIII in illustrating the complex relationship between companies and workers that characterize "social Catholicism".[5]
2 September – The letters of protest directed towards the Fascist Italian government in the Dobbiamo Intrattenerla and Non Abbiamo Bisogno obtain partial success, with an agreement being signed with the Italian government recognizing again the Italian Catholic Action, but in a weaker diocesan form without a central direction.[5]
2 October – Pope Pius XI publishes the minor encyclical Nova impendet [es] ("New Questions Threaten"), in which he addresses the Great Depression economic crisis affecting many unemployed workers partnered with the rise in military spending among nations.[8]
1930–1933 – SoS Cardinal Eugenio Pacelli makes attempts to obtain German a treaty for protection and continued rights of the Catholic Church and her Priests in the nation with the representatives of successive German governments, which turn out ultimately unsuccessful.[11][12]
Deaths
There were no deaths in the year 1931 in Vatican City.[13]