Relatively little research has focused on the role that positive psychological characteristics, such as optimism, might play in the mitigation of stressors and reduction of psychopathology. Dispositional optimism is a trait-like characteristic reflecting a positive attitude or mood regarding the future. This study examined the moderating effect of dispositional optimism on the relationship between negative life experiences and suicide ideation and attempts in a college student sample. Negative life events were associated with current suicide ideation and previous suicide attempts, and dispositional optimism moderated these relationships, after controlling for hopelessness and severity of depression. Individuals with greater optimism have reduced risk for suicide ideation and attempts in the face of low to moderate negative life events; however, this association is changed at the highest levels of negative life events. Implications for 123 treatment include strengthening active and future-focused coping in patients who have experienced negative or potentially traumatic life events to protect against suicidal thoughts and behaviors.