Strong links have been documented between life events and the course of bipolar disorder. Laboratory studies of stress provide an opportunity to understand the mechanisms involved in reactivity to stressors, but few such studies have been done in the bipolar field. In the current study, 28 people with bipolar I disorder in full or partial remission and 40 people with no history of a mood disorder were randomly assigned to 1 of 3 conditions involving different levels of failure feedback on a concept formation task. Confidence, affective reactions, and performance on a subsequent anagram task were assessed. Results provide tentative support for reactivity to the stressor among the bipolar group, although reactivity was limited to impaired anagram performance.