What do human beings use conditional reasoning for? A psychological consequence of counterfactual conditional reasoning is emotional experience, in particular, regret and relief. Adults’ thoughts about what might have been influence their evaluations of reality. We discuss recent psychological experiments that chart the relationship between children’s ability to engage in conditional reasoning and their experience of counterfactual emotions. Relative to conditional reasoning, counterfactual emotions are late developing. This suggests that children need not only competence in conditional reasoning, but also to (...) engage in this thinking spontaneously. Developments in domain general cognitive processing (the executive functions) allow children to develop from conditional reasoning to reasoning with counterfactual content and, eventually, to experiencing counterfactual emotions. (shrink)