The recently proposed self-appraisal model of Type A behavior holds that Type As desire an accurate appraisal of abilities, and respond to uncertainty about abilities with exaggerated attempts to generate diagnostic information. The model also predicts that the major emotional response to uncertainty for Type As is anxiety. A study was conducted in which 80 college students classified as either Type As or Type Bs were induced to succeed or fail on a task where they were either very certain or very uncertain of their subsequent ability levels. Subjects completed questionnaires, performed anagram problems, received performance feedback indicating either success or failure, and completed other questionnaires measuring mood and performance attributions. The results indicated that task failure, compared to success, produced greater depression, anger, and frustration for all subjects. Consistent with the self-appraisal model prediction, uncertainty (regardless of success or failure) led to increased anxiety for Type As, but not for Type Bs. In fact, increased uncertainty produced lower anxiety for Type Bs, suggesting that Type As and Type Bs differ dramatically in their emotional responses to uncertainty about abilities. (Author/NB)