Student evaluations of teaching (SETs) are an important point of assessment for faculty in curriculum development, tenure and promotion decisions, and merit raises. Faculty members utilise SETs to gain feedback on their classes and, hopefully, improve them. The question of the validity of student responses on SETs is a continuing debate in higher education. The current study uses data from two universities (n = 596) to determine whether and under what conditions students are honest on in-class and online SETs, while also assessing their knowledge and attitudes about SETs. Findings reveal that, while students report a high level of honesty on SETs, they are more likely to be honest when they believe that evaluations effectively measure the quality of the course, the results improve teaching and benefit students rather than the administration, and when they are given at the end of the term. Honesty on evaluations is not associated with socio-demographic characteristics.