The purpose of the study was to explore predictors of discontinuation of oral contraceptives (OC) including pre-OC use characteristics and adverse physical, emotional, and sexual effects of OCs. Women aged 18+ years in committed, sexually active relationships were assessed before starting OC and reassessed at 3, 6, and 12 months or shortly after discontinuation. Assessment included pre-OC use attitudes and expectations about the pill; self-reported side effects and perimenstrual symptoms including premenstrual syndrome (PMS); physical and emotional well-being; and sexual interest, enjoyment, and frequency of sexual activity. Seventy-nine women completed the study, 38% continued OCs, 47% discontinued, and 14% switched to another OC. Emotional side effects, worsening of PMS, decreased frequency of sexual thoughts, and decreased psychosexual arousability correctly categorized 87% of cases by using logistic regression. Emotional and sexual side effects were the best predictors of discontinuation/switching, yet such OC effects have been largely ignored in the research literature.