Quantitative breast MRI data was acquired at seven clinical sites using the CaliberMRI phantom. T1 and DWI data were acquired, and the qCal software was used for analysis. Protocol adherence was assessed, quantitative measures were automatically derived, and variability between measurements was evaluated. Going forward, the phantom will be used for calibration as part of a program to assess quantitative accuracy in a large multi-site clinical trial. The phantom program will be expanded to other sites in the trial, with standardized reporting used to understand variability across sites.