Although optimism is generally regarded as a positive dispositional characteristic, unmitigated optimism can be problematic. The adaptiveness of overly optimistic expectations in novel or unfamiliar settings is questionable because individuals have little relevant experience on which to base such expectations. In this four-phase longitudinal study we examined over-optimism in students when making the transition from a familiar academic setting (high school) to a novel academic setting (college). In particular, we focused on the efficacy of attributional retraining (AR), a control-enhancing intervention, to ameliorate the scholastic transition of overly optimistic students in terms of academic-related causal attributions and control perceptions, course grades, and overall GPAs. Results suggest that overly optimistic college students who did not receive the AR intervention increasingly endorsed maladaptive causal explanations for academic performance, and performed at the same level as students with extremely low optimism. Conversely, as expected, over-optimists who received the AR intervention significantly increased in their use of adaptive causal explanations and perceptions of control, in addition to academically outperforming the no-AR/over-optimists. These findings indicate that the potential risks associated with over-optimism may be reduced by pairing optimism with AR to induce adaptive cognitions, thereby facilitating achievement.