Elevated coronary artery calcium (CAC) score, as assessed by the Agatston method, is associated with incident atrial fibrillation (AF). We aimed to evaluate the associations of CAC volume and density with incident AF. Participants from the Multiethnic Study of Atherosclerosis without baseline AF and CAC >0 were included. The associations between baseline and progression (average annual change) of CAC measures and incident AF were evaluated using Cox proportional hazards models. CAC volume and Agatston scores were natural log (ln)-transformed, and hazard ratios (HRs) were calculated per standard deviation increment. The baseline analysis included 3,332 participants; 2,643 were included in the progression analysis. In multivariable models adjusted for cardiovascular risk factors, volume (HR 1.24, 95% confidence interval [CI] 1.14 to 1.36), density (HR 1.14, 95% CI 1.05 to 1.25), and Agatston score (HR 1.24, 95% CI 1.14 to 1.35) were associated with increased risk of incident AF. In models including both volume and density, the magnitude of association between volume and incident AF was unchanged, whereas the density association was eliminated (HR 0.99, 95% CI 0.89 to 1.11). Median time to follow-up CAC assessment was 1.9 (interquartile range 1.3, 3.0) years. Similar results were observed for the association of incident AF with annual change in volume and Agatston score. CAC volume, but not density, is associated with risk for incident AF when adjusting for both. In conclusion, our findings suggest that, although CAC may be a risk marker for AF, the association between CAC and AF appears to be independent of plaque density.