Abstract Young children are notoriously bad at understanding ironical statements, with irony comprehension emerging around the age of 6 and appearing resistant to task manipulation. What can explain this late emergence? We propose that children’s epistemic vigilance is a pivotal component of the constellation of socio-cognitive abilities underpinning irony comprehension. Epistemic vigilance enables children to detect the contextual incongruity of an ironical statement, discern that the ironical speaker is neither mistaken nor deceptive, and infer the critical, dissociative attitude expressed through verbal irony. By highlighting the role of epistemic vigilance, this account provides insight into the developmental puzzle of irony comprehension. It elucidates why its developmental trajectory diverges from that of other forms of figurative or humorous language and why it is closely linked to lie understanding and second-order false belief reasoning.