We investigated adults' ability to detect children's prepared and unprepared lies and truths. Furthermore, we examined children's strategies when lying. Thirty children (11–13 years) were interviewed about one self-experienced and one invented event each. Half had prepared their statements, the other half not. Sixty adult observers assessed the veracity of 10 videotaped statements each. Overall deception detection accuracy (51.5%) was not better than chance. The adults showed higher accuracy for unprepared statements (56.6%), than prepared statements (46.1%). The adults reported to have used more verbal than nonverbal cues to deception, especially the Detail criterion. The most frequent verbal strategy reported by the children was to use real-life components (e.g. own or others' experiences); the most frequent nonverbal strategy was to stay calm. Arguably, the low accuracy is due to adults' failure to see through the lying children's strategies. Copyright © 2006 John Wiley & Sons, Ltd.