The purpose of this study was to estimate risk factors for the deterioration and improvement of premenstrual mood disturbance with oral contraceptive pill use. Predictors of the deleterious and beneficial effects of oral contraceptive pill use on premenstrual mood were analyzed with the use of logistic regression in a nested case-control study within a community-based cohort of 976 premenopausal women in Massachusetts. Of 658 women who were using oral contraceptive pills, 16.3% of the women reported oral contraceptive pill–related premenstrual mood deterioration, and 12.3% of the women reported premenstrual mood improvement. In adjusted models, previous depression was the only significant predictor of mood deterioration (odds ratio, 2.0; 95% CI, 1.1-3.8); early-onset premenstrual mood disturbance and dysmenorrhea were significant predictors of oral contraceptive pill–related mood improvement (odds ratio, 3.1 95% CI, 1.9-5.2 and odds ratio, 2.3 95% CI, 1.4-3.9, respectively). Oral contraceptive pills do not influence premenstrual mood in most women. Premenstrual mood is most likely to deteriorate in women with a history of depression and to improve in women with early-onset premenstrual mood disturbance or dysmenorrhea.