NIST Traceable Color Transmission Calibration Slides are used to assess and calibrate the color accuracy of microscopy measurement systems. These slides feature 24 large color patches with diameters from 4150µm, calibrated for spectral transmission, down to 150µm. NIST traceable calibration data is included for these serialized and calibrated slides to facilitate accurate conversion of the color patches to other color spaces of interest such as Adobe RGB 1998, CIE L*A*B* and XYZ. These NIST Traceable Color Transmission Calibration Slides include a calibration certificate, a calibration data report, a conversion spreadsheet, a USB flash drive with electronic calibration information, and a protective storage case. A protective glass cover over the color film minimizes deterioration of the calibrated color patches and also allows for compatibility with oil immersion objectives.