Analysis of instant messaging deception has never been conducted using real-world data. This study tracked and analyzed deceptions in participants? real-life instant messaging conversations, analyzing them on a message-by-message basis instead of merely a conversation-by-conversation basis. The results show that people frequently deceive in instant messaging, and that the magnitude of these deceptions is positively correlated with instant messaging use. Deceptions are told in clusters, suggesting strategic usage of deception in instant messaging, and although people underestimate how frequently they deceive, they have a very good sense of how much they are straying from their normal deception rates.