This study evaluated the use of a modified Flanders Interaction Analysis (MFIA) to provide feedback and improve faculty lecturing quality at two Munich universities. Twenty-two faculty volunteers were randomized into experimental and control groups. Both groups gave lectures evaluated by MFIA, but only the experimental group received feedback. Compared to their initial lectures, the experimental group showed significant improvements in indirect teaching responses, student interaction and engagement, organization, empathy, and case-based teaching after receiving MFIA feedback. Student evaluations also significantly improved for several criteria after the experimental group's MFIA intervention. The study suggests MFIA is an effective, economical way to provide feedback and help faculty improve their lecturing skills.