Lecturing is often touted as a means to inspire students' interest, despite evidence that most lectures fail to do so. This study examines triggers of students' situational interest during lectures. Students (N = 706) in 12 different individual one hour first year lectures in a UK university were surveyed at the end of the lecture. They described the moment they were most interested; rated a series of 5 point Likert scale items on their situational and individual interest, and features of the content, presentation and teacher's behaviour during that moment; and provided demographic characteristics. Simultaneous regression analyses showed that novelty, cognitive activation, cognitive incongruity, and utility value all positively predicted situational interest. Students' level of individual interest and their perceptions of their teacher's enthusiasm, approachability and knowledge were the strongest predictors of situational interest. Overchallenge was negatively associated with situational interest.