Eight laboratories participated in a round robin to evaluate variations in aggregate gradation when tested using Masonry cement and Portland cement-lime masonry mortars. A control gradation was used which,was near the center of C144 gradation limits and five other gradations were used which tested the limits of C144. It appears from the data that the limits on C144 can be broadened without appreciably altering the safety built in for user protection. Although not part of the original test program, a study was made of the yield of the various mortars produced, and it was determined that the masonry cements had on average a 5.3% increase in volume over the Portland cement-lime mixes.