This article reports on a study which aimed to determine the effect of strength of accent on listening comprehension of interactive lectures. Test takers (N = 21,726) listened to an interactive lecture given by one of nine speakers and responded to six comprehension items. The test taker responses were analyzed with the Rasch computer program WINSTEPS to investigate the relative difficulty of the items associated with the nine versions of the interactive lectures. Results indicated that comprehension of interactive lectures was diminished with quite light accents, as has been found with monologic lectures.