Can overtrust in robots compromise physical security? We posi- tioned a robot outside a secure-access student dormitory and made it ask passersby for access. Individual participants were as likely to assist the robot in exiting the dormitory (40% assistance rate, 4/10 individuals) as in entering (19%, 3/16 individuals). Groups of people were more likely than individuals to assist the robot in entering (71%, 10/14 groups). When the robot was disguised as a food delivery agent for the �ctional start-up Robot Grub, individ- uals were more likely to assist the robot in entering (76%, 16/21 individuals). Lastly, participants who identi�ed the robot as a bomb threat demonstrated a trend toward assisting the robot (87%, 7/8 individuals, 6/7 groups). �us, overtrust—the unfounded belief that the robot does not intend to deceive or carry risk—can represent a signi�cant threat to physical security at a university dormitory.