Retinger's brother, Juliusz, taught physiological chemistry at the University of Chicago and University of Wilno. Retinger himself initially considered a career in the priesthood, but three months in the Jesuit novitiate in Rome confirmed he would not be suited to the life. Further financed by Count Zamoyski in 1906, Retinger entered simultaneously the Ecole des sciences politiques and the Sorbonne in Paris and two years later, aged twenty, became the youngest person ever to earn a Ph.D. in literature from there. While in the French capital, armed with introductions from Zamoyski and his own relative, the salonnière and pianist Misia Sert, he moved in intellectual circles and was befriended by among others, André Gide, François Mauriac, , Jean Giraudoux, Erik Satie and Maurice Ravel. His early literary ambitions were stopped in their tracks when he presented his first novel, ""Les Souffleurs"" to André Gide for his opinion. Gide told him: "Joseph, you will never be a writer." He next went to Munich to study comparative psychology for a year. From there, encouraged by Zamoyski, in 1910 he moved to England, where he entered the London School of Economics for a year's study and began a lobbying operation on behalf of the Polish cause and its populations scattered across three ailing empires. Formally he became Director of the London Office of the Polish National Committee (1912–1914). During this time he continued to move in élite circles and thanks to an introduction by Arnold Bennett whom he had met in Paris, Retinger developed a close friendship with his older Polish compatriot, the already well established novelist, Joseph Conrad. Retinger urged Conrad to visit Poland, and on 28 July 1914, the day World War I broke out, Retinger, his wife Otolia, and Conrad, his wife, and their two sons arrived in Kraków, the two men's childhood stamping grounds (they were alumni of the same secondary school). Due to the closeness of the Russian border (Russia was then allied to Great Britain), the Conrads soon sought greater safety in the Tatra Mountains resort of Zakopane. Retinger would write about Conrad in his 1943 book, "Conrad and His Contemporaries". Historian Norman Davies suggests that it was probably Conrad who introduced the "polyglot and polymath" Retinger to the British intelligence services. Later Retinger became a personal friend of Major-General Sir Colin Gubbins, wartime head of SOE, and after the war an MI6 "asset".