Tis article analyses several aspects of the administrative policy of Julian the Apostate in the western half of the Roman Empire (first as the сaesar under Constantius II, from 355 to 360 AD, and then as the augustus from 361 to 363). Taking the narrative, legislative, and epigraphic sources, analysed with the prosopographic method, into account, the author explores the relationship of Caesar Julian with the elites of the West and the features of social mobility in the West under Julian as independent ruler after 361. The author has run to conclusion that Julian the Apostate’s administrative policy in the promotion to senior positions divided into several stages. At the first stage, Julian tried just to strengthen his own position and not changed the existing order. In this period, he had to accept the orders from his cousin Constantius II. The second stage was under the preparation for the war with Constantius II, when Julian changed the military and civilian elite. In the third period, Julian tried to legitimize his power and reach an agreement with the Roman Senate. In social terms, most of Julian’s appointees were the “new people,” or the officials, persons of liberal professions, and military men of barbarian origin. The religion of the appointees did not matter. The suggestion of the Gauls dominating among Julian’s appointees does not work.