Bulk oxide determinations from a pair of portland cements provides the basis for calculation precision and accuracy values for X-ray fluorescence (XRF) analysis for both the fused glass bead and the pressed powder sample preparation. Approximately 45 laboratories provided six replicates analyzed in duplicate for two separate portland cements covering eleven analytes, CaO, SiO2, Al2O3, Fe2O3, SO3, MgO, Na2O, K2O, TiO2, P2O5, and Cl, with the laboratories roughly split between the two different sample preparations. Chemical data using traditional chemical analyses (the Reference Methods) from the Cement and Concrete Reference Laboratory (CCRL) proficiency test program were included for comparison to the XRF results.