The present experiment examined the role of cognitive flexibility in the consistency of truth tellers' and liars' reports. We expected liars to be less flexible (less able to report an experience in different ways) and hence less consistent than truth tellers when asked to describe an event in different ways (e.g. verbally and pictorially). In the experiment, truth tellers entered a room and performed several tasks, whereas liars did not enter the room or perform the tasks but attempted to convince an interviewer that they did. Truth tellers and liars were interviewed twice about the room and tasks, and were asked to express their answers either the same way on both interviews (e.g. verbally then again verbally) or in different ways (e.g. verbally then pictorially). In support of the cognitive flexibility hypothesis, liars' reports were less consistent than truth tellers' reports, particularly when reporting in different ways across interviews. Theoretical and practical implications are discussed. Copyright © 2012 John Wiley & Sons, Ltd.