Dressing formally or informally as an academic may be a trade-off when it comes to managing impressions towards students, but the extant body of literature remains limited with only mixed results. This research is the first focussed investigation to examine the effects of academic dress formality on the 'big two' of impression formation, perceptions of warmth and competence. In a series of three controlled laboratory experiments (total N = 1361), we find dress formality to increase perceptions of competence but to decrease perceptions of warmth, which leads to 'downstream' effects on students' evaluations of instructors and behavioural intentions to enrol in a course. Furthermore, we demonstrate that perceptions of competence may be subject to other information cues (success communication and discipline norms) that can mitigate negative effects associated with dress informality. Implications for higher education practitioners are provided.