College students were identified who were unrealistically optimistic about the likelihood they would experience severe problems due to alcohol consumption. These individuals were then followed over a 2-year period to determine whether they were more likely to report experiencing a range of alcohol-related negative events. Unlike the majority of studies on unrealistic optimism, this study (a) assessed bias at the individual rather than group level and (b) used a prospective rather than cross-sectional design. Participants completed measures at four times, each separated by 4-6 months. Findings showed that unrealistic optimism at Time 1 was associated with a greater number of negative events at Times 2, 3, and 4. Similarly, unrealistic optimism at Time 2 was associated with more negative events at Times 3 and 4. In all cases, the relationships were significant when controlling for previous negative events, suggesting the effects of unrealistic optimism can mount over time.