Vigilance towards deception is investigated in 3- to-5-year-old children: (i) In Study 1, children as young as 3 years of age prefer the testimony of a benevolent rather than of a malevolent communicator. (ii) In Study 2, only at the age of four do children show understanding of the falsity of a lie uttered by a communicator described as a liar. (iii) In Study 3, the ability to recognize a lie when the communicator is described as intending to deceive the child emerges around four and improves throughout the fifth and sixth year of life. On the basis of this evidence, we suggest that preference for the testimony of a benevolent communicator, understanding of the epistemic aspects of deception, and understanding of its intentional aspects are three functionally and developmentally distinct components of epistemic vigilance. (Contains 1 figure and 1 table.)