People differ in the extent to which their self-evaluations fluctuate in response to positive and negative events. This research tests whether self-ambivalence predicts this self-evaluative reactivity. Participants first completed measures of self-ambivalence and baseline self-esteem. Next, they were induced a success or failure experience in a cognitive task and finally rated their cognitive self-evaluations (taskspecific ability, state self-esteem) and affective reactions (self-feelings, mood). Self-ambivalence was associated with stronger effects of the success/failure manipulation on cognitive self-evaluations but not on affective reactions, with baseline self-esteem controlled. Possible underlying mechanisms are discussed.