Fifty preschool children (mean age 3:11 years) took part in an investigation of the relations between children's executive function performance, their understanding of mind and their language skills. The study demonstrates the feasibility of testing rudimentary executive function skills among preschoolers, using an original battery of tasks. The results were consistent with those from studies of older children (e.g. Welsh, Pennington & Groisser, 1991), in that three aspects of executive function were distinguished: working memory, attentional flexibility and inhibitory control. In addition, specific links were found between executive function and theory-of-mind performance, even when age and both verbal and non-verbal ability were taken into account. In particular, children's deceptive abilities were closely related to success on tests of inhibitory control. The implications of these results for our understanding of deceit are discussed.