Context: There is great interest in the biology of vascular calcification. Wnt/beta-catenin signaling is an important mediator of mineralization and may play a role in vascular calcification. Objective: We assessed the association between circulating Wnt antagonists and abdominal aortic calcification (AAC) severity in elderly women. Design: This was a cross-sectional analysis of the Calcium Intake Fracture Outcome Study. Setting: The participants were recruited from the community-dwelling elderly population. Participants: We examined 768 women aged over 70 years. Interventions: We collected blood samples, and lateral spine images captured during bone density assessment were used to score AAC with a validated 24-point scale. Main Outcome Measures: We tested the hypothesis that low Wnt antagonist levels of Dickkopf-1 (DKK1), secreted frizzled related protein 3 (sFRP3), and Wnt inhibitory factor 1 (WIF1) are associated with severe AAC (AAC24 score > 5). Results: Severe AAC was present in 146 women (19%). Lower levels of DKK1, but not WIF1 and sFRP3, were associated with higher odds of severe AAC. Per standard deviation decrease in DKK1 was associated with increased multivariable-adjusted odds ratio (OR) of severe AAC [OR, 1.26; 95% confidence interval (CI), 1.04 to 1.52; P = 0.017]. In quartile analyses, the lowest and second-lowest quartiles of DKK1 had increased multivariable-adjusted odds of severe AAC vs the highest quartile (OR, 2.05; 95% CI, 1.18 to 3.56; P = 0.011 and OR, 1.83; 95% CI, 1.05 to 3.19; P = 0.035). Conclusions: In elderly women, DKK1, but not sFRP3 or WIF1, is associated with severe AAC. This study supports the concept that Wnt/beta-catenin signaling is an important regulator of vascular mineral metabolism and is independent of other risk factors.