The counterfactual emotions of regret and relief arise from considering how the present would look had one taken an alternative past action. We investigated if 4- to 9-year-old children (N = 192) could identify others' regret and relief by watching videos of actors choosing between two boxes that concealed a better or worse prize. Each actor first looked inside the chosen box and made a happy or sad facial expression, and children were then shown the contents of that box. Critically, the actor then looked inside the non-chosen box and made either a happy or sad facial expression, and children were asked what they thought was inside. Children aged 6 years and older were able to identify that the non-chosen box concealed a better prize when the actor was sad, and a worse prize when the actor was happy. The abilities to experience and recognise counterfactual emotions may develop concurrently.