Two studies investigated in which situations teachers (would) investigate whether a student was lying or telling the truth and how these situations were perceived. Results of Study 1 indicate that teachers (would) interview students when it comes to use of unfair means, aggressive behavior, theft, absence without permission, bullying, and vandalism, whereat deceitful situations with rather light consequences were most frequently described. Moreover, participants perceived the frequency of occurrence of all situations as lower for themselves compared to colleagues. In both studies, the use of unfair means, absence without permission, and bullying (over a longer period) were rated as most frequently occurring in everyday school life. Further, deception detection was perceived as being mostly important in situations with severe consequences. Study 2 also demonstrates that situations with light consequences are perceived as situations where it is of relatively less importance to make accurate judgments, avoid wrongful accusation, and detect misbehavior, as compared with situations with severe consequences. Overall, teachers perceive avoiding wrong accusation as more important than detecting misbehavior. Influences of teachers' perceptions on their behavior are discussed.