We investigated whether young children are curious about what could have been ("counterfactual curiosity"). In two experiments, children aged 4 and 5 years (N = 32 in Experiment 1, N = 24 in Experiment 2) played a matching game in which they turned over cards in the hope that they matched a picture. After choosing a card, children could use "x-ray glasses" to uncover unchosen cards. In Experiment 1, most children spontaneously used the glasses to peek at past alternatives, even when the outcome could no longer be altered. In Experiment 2, children concentrated their information search on alternatives that were within their control. In both experiments, children showed greater interest in counterfactual outcomes when the card they chose turned out not to match the picture. The findings suggest that young children are curious not only about what is but also about what could have been. Curiosity about alternative outcomes seems to precede counterfactual reasoning.