Members of an international standards working group for silica measurement (ISO/TC146/SC2/WG7 Silica) collaborated to assess the differences between sample preparation approaches for the analysis of respirable crystalline silica (RCS) by X-ray diffraction (XRD). They also assessed the relative collection efficiencies of 13 respirable samplers. The evaluation involved nine laboratories from eight countries. Samplers were exposed to airborne concentrations of ultrafine and medium Arizona road dust (ARD) in a calm air chamber. Each participating laboratory analysed samples following their own method and the Health and Safety Laboratory (HSL) retained a third of the samples for verification. All methods and analytical approaches applied in this study obtained comparable results (most were within 12 %). An exception was a method used with the CIP10 R sampler, which reported lower values. Correcting for the crystallinity of the calibration quartz dust using a verified value tested against a certified reference material has one of the largest impacts on the comparability of results. When following good analytical practice, the main factors affecting the comparability of results for RCS are significant differences in sampler efficiencies. In particular, the conductive sampler from SKC obtained a higher concentration of respirable dust (1.3–1.4×) when compared with the average air concentration. The Dorr Oliver, SKC aluminium, CIP10 R, and IOM head (with polyurethane foam separator) samplers all reported lower respirable dust air concentrations than average with the ultrafine ARD. Their lower collection efficiency compared with other samplers is explainable from published sampler information. The Dorr Oliver sampler also had a tendency to collect a lower proportion of RCS in the respirable dust than others. The working group propose that more stringent particle size selection and mass collection criteria are used to improve consistency and cross-utilisation of exposure data between countries.