Three laboratories independently conducted round-robin testing for determining percentage water absorption and bulk specific gravity of several types of dimension stone. The primary objectives of the study were to evaluate interlaboratory variation associated with this testing, to evaluate the influence of the wetting method between ASTM and European procedures, and to better understand the effect of specimen shape/size and immersion duration. Each laboratory tested 15 different stone types of varying shape and size in accordance with ASTM C97, Standard Test Methods for Absorption and Bulk Specific Gravity of Dimension Stone. Specimen sizes included 3- and 2-in. cubes to evaluate the effect of the limits of ASTM specimen size requirements on test results. Subsequent testing was performed on 1½-in.-thick and ⅜-in.-thick plates cut from the 3-in. cube specimens to evaluate the effect of reduced specimen thickness on test results, as the fabrication of 2-in. minimum cube specimens is often impractical (e.g., stone tile or thin-stone cladding) and in some cases not possible (e.g., forensic evaluation of thin applications). The laboratories also tested the absorption of each stone type in accordance with the European Standard EN 13755 to evaluate the effect of the prescribed wetting method that differs from the ASTM method. The EN procedure prescribes the gradual immersion of specimens, whereas the ASTM procedure prescribes immediate and complete immersion. The EN procedure also prescribes weighing the wetted specimens every 24 h until constant mass is achieved, whereas the ASTM procedure prescribes 48-h immersion. Results of this testing are presented in figures and tables to compare the results from the three laboratories and analyze the effects of differences in the wetting method, specimen shape/size, and immersion duration on property determination. This paper provides an interpretation and discussion of the test results and presents proposed modifications to the ASTM C97 test procedure as appropriate (e.g., longer immersion duration or accommodation for thin specimens).