Undergraduate study behaviours, principally lecture attendance and additional study, are shown to predict better student achievement by many researchers. Despite this, there is not much evidence on the determinants of these behaviours. This is the first paper to explore the determinants of study behaviours across multiple subject areas; and is the first to incorporate students' noncognitive traits into such a model; that the authors are aware of. This enables the formation of policy that can improve academic achievement by encouraging study behaviour. The results show that students' noncognitive traits, in particular conscientiousness and future-orientation, are important determinants of lecture attendance and additional study hours. In fact, there is very little that explains undergraduate study behaviour besides noncognitive traits. Standard economic factors, such as family income, financial aid and parental transfers, are not predictive of study behaviours. Some comments are provided on a potential behavioural economics approach to encouraging study behaviours. (Contains 2 tables and 2 figures.)