Development of affective decision-making was studied in 48 children at two ages (3 and 4 years) using a simplified version of the Iowa Gambling Task (Bechara, Damasio, Damasio, & Anderson, 1994). On each of 50 trials, children chose from 1 of 2 decks of cards that, when turned, displayed happy and sad faces, corresponding to rewards (candies) won and lost, respectively. Cards in 1 deck offered more rewards per trial, but were disadvantageous across trials due to occasional large losses; cards in the other deck offered fewer rewards per trial, but were advantageous overall. On later trials, 4-year-olds made more advantageous choices than 3-year-olds, and 4-year-olds made more advantageous choices than would be expected by chance, whereas 3-year-olds made more disadvantageous choices than would be expected by chance. These findings, which were especially pronounced for girls, indicate that affective decision-making develops rapidly during the preschool period, possibly reflecting the growth of neural systems involving orbitofrontal cortex.