Teens often engage in risk taking. Avoiding risk may be aided by rapid access to cognitive models for danger. This study investigated whether these schemata are immature in adolescence. An N400 sentential priming paradigm compared risky, predictable, and incongruent sentence processing in adolescents and adults. Adults and teens processed predictable sentences similarly, as evidenced by equivalent N400 priming. However, in adults, more activation was required to access final words in a risky sentence than when the situation was predictable and benign. Conversely, teens showed little difference in N400s generated by risky or expected sentences. This suggests that risky scenario final words were unexpected for adults but not for adolescents because of age-related differences in world knowledge and risk-related schemata. This study may help to explain why teenagers engage in risky activities when there is little time for deliberative thought.