This paper presents the results of a research project on the properties of masonry grout and grouted concrete masonry. Seventy-two grout specimens were tested to investigate the effect of varying the proportions of grout (cement to aggregate ratio) on the physical properties of grout and grouted concrete masonry including compressive strength and modulus of elasticity. Both fine and coarse aggregate grouts were investigated. The investigation included a comparison of the compressive strength of grout specimens saw cut from grouted hollow concrete masonry units versus the procedures of ASTM C1019 . Compressive strength tests of grouted and ungrouted concrete masonry prisms were also conducted. This experimental investigation concludes that grout having leaner proportions (cement to aggregate ratio) than permitted by ASTM C476  may be more compatible with typical concrete masonry units. It is recommended that the strength requirements of grout be developed as an alternate to the current proportion requirements of ASTM C476 in order to encourage designers to specify grout with properties similar to the properties of the concrete masonry units thus achieving compatibility of the components and improve the structural performance of grouted concrete masonry structures. It was also found that grout specimens molded in accordance to ASTM C1019 can be used to predict the strength of grout in grouted concrete masonry.