In new or uncertain situations, we must often learn through experience to make choices likely to result in good outcomes and to avoid those that may yield bad outcomes. Past research suggests that individuals differ in this trial-and-error learning, with some preferentially incorporating good outcomes into their subsequent evaluations, and others weighting bad outcomes more heavily. Such valence biases in learning may additionally influence what we later remember about our experiences. Adolescents have been proposed to be particularly sensitive to rewarding experiences, a tendency which may foster a propensity for risky choice. In the present study, we examined whether valence asymmetries in reinforcement learning change across adolescent development, conferring age differences in risk preferences, and whether individual learning asymmetries might also bias subsequent memory. Participants ages 8-27 chose between pairs of probabilistic and deterministic “point machines” to learn their associated reward outcomes. Trial-unique images were presented with the outcome of each choice, and incidental memory for these pictures was tested immediately following the learning task. Counterintuitively, adolescents exhibited less risk taking than children and adults, corresponding to a bias toward overweighting worse- relative to better-than-expected outcomes during reinforcement learning. Incidental memory was also modulated by valence biases in learning, such that individuals who learned more from worse-than-expected outcomes were more likely to remember the trial-unique images that coincided with them, and vice versa. Collectively, these results highlight age-related changes across adolescence in the computation of subjective value, and demonstrate that a valence asymmetric valuation process also influences how information is prioritized in episodic memory.