Employing the stress and coping theory of Lazarus and Folkman, this study followed 117 women age 40 or over regarding personality, cognitive appraisal, coping, and mood variables before breast biopsy, after diagnosis, and, for those who had cancer, after surgery. Upon biopsy, 36 received a cancer diagnosis, and 81 received a benign diagnosis. The 2 groups did not differ on appraisals, coping, or affect before diagnosis. With prebiopsy affect controlled, cancer patients reported more negative affect postbiopsy than did benign patients. Postsurgery, cancer patients expressed less vigor and more fatigue than benign patients, but the groups did not differ on other negative emotions. Prebiopsy, psychosocial predictors accounted for 54% and 29% of the variance in negative and positive emotion, respectively. Prebiopsy variables also predicted postbiopsy and postsurgery mood; cognitive avoidance coping was a particularly important predictor of high distress and low vigor.