Ammianus recounts two specific episodes to illustrate the characater of C. Ceionius Rufius Volusianus signo Lampadius, praefectus urbi at Rome in 365/6 (27.3.5-8), whom he presents as vain and pompous, though he occasionally showed himself "severus et frugi." The second episode presents no problems of interpretationl: during Lampadius' prefecture there were frequent riots, in one of which the lowest classes of the city almost succeeded in burning down one of his town-houses, provoked by his illicit seizure of metals for in use his buidling and restoration projects. The first episode, however, has been seriously misdated and hence probably misinterpreted by the consensus of scholarship. Ammianus introduces it with the clause "hic cum magnificos praetor ederet ludos et uberrime largiretur." This has so far always been construed as "when this man was gving magnificent games as praetor etc.," so that the episode has always been dated three decades before Lampadius' urban prefecture. I shall demonstrate on both philological and historical grounds that Ammianus refers to the games put on by the praetor of 366, which provoked the jealousy of Lampadius when he was in office as praefectus urbi. In the light of this newly established context, I shall consider who are most likely to be the beggars whom Lampadius summoned from the Vatican and to whom he gave lavish gifts ("accitos a Vaticano quosdam egentes opibus ditaverat magnis").