ARTICLE ABSTRACTBackground: Cancer screening aims to detect cancer at an asymptomatic stage, although side effects from screening also occur. We investigated the prevalence, longitudinal development, and predictors of psychosocial consequences of false-positive breast cancer screening.Methods: Three hundred ninety-nine women with false-positive screening mammography responded to the Consequences of Screening–Breast Cancer (COS-BC) questionnaire immediately after a negative diagnosis (free from breast cancer) following recall examination(s) (baseline), and 6 and 12 months later. Age-matched controls (n = 499) with a negative mammogram responded to the COS-BC at the same occasions. Five COS-BC scales (Sense of dejection, Anxiety, Behavioral, Sleep, and Existential values) were used as outcome measures.Results: Women with false-positive mammography had consistently higher prevalence of all five consequences compared with controls (P < 0.001). The prevalences decreased between baseline and 6 months (P < 0.001) but were stable between 6 and 12 months (P ≥ 0.136). Early recall profoundly predicted long-term consequences for all five outcomes (OR, 3.05–10.31), along with dissatisfaction with information at recall (OR, 2.28–2.56), being foreign-born (OR, 2.35–3.71), and lack of social support (OR, 1.13–1.25).Conclusion: This 1-year longitudinal study shows that women experience psychosocial consequences of false-positive screening mammography. Early recall should be performed cautiously, and provision of information as well as social support may reduce psychosocial consequences.Impact: Although delivery of population-based screening reduces breast cancer mortality, it also raises the issue of its impact on the psychosocial well-being of healthy women. Our findings identify predictors that can be targeted in future efforts to reduce the side effects of mammographic screening. Cancer Epidemiol Biomarkers Prev; 24(9); 1388–97. ©2015 AACR.