Concrete hollow block masonry is a versatile and reliable construction method that offers strength, ductility, and durability due to its modular suitability, cost-effectiveness, and capability of accommodating grout and reinforcement. The axial compressive strength and diagonal tensile strength (in-plane shear) are key parameters to design masonry structures. Although numerous studies investigated the compressive strength of concrete masonry prisms, limited studies have been conducted to identify the effect of grouting and reinforcement on the diagonal tensile strength of masonry assemblages constructed with full-scale units. This study experimentally investigates the diagonal tensile strength of full-scale masonry assemblages (i.e., wallets) and the compressive strength of their masonry prisms counterparts. Nine full-scale wallets with dimensions of 1.2 × 1.2 m in accordance with ASTM E519 (ASTM E519-20 standard test method for diagonal tension (shear) in masonry assemblages. West Conshohocken, PA. United States, 2020) were constructed to yield three groups of specimens, namely, fully grouted wallets with a reinforcement ratio of 0.42%, partially grouted wallets with a reinforcement ratio of 0.17%, and ungrouted wallets. The axial compressive strength of grouted and ungrouted prisms was also investigated. Six full-scale concrete masonry prisms were constructed and tested under axial compression loading in accordance with CSA S304 (CSA S304-14 Design of Masonry Structures. Mississauga, Ontario, Canada, 2014). The prisms were divided into two groups: grouted and ungrouted prisms. The results showed that the diagonal tensile strength of fully and partially grouted wallets was significantly higher than that of the ungrouted wallets by 371% and 256%, respectively. The reinforcement was found to increase the shear strain capacity of the wallets after the initiation of the first crack. In addition, the grouting of masonry prisms had no significant influence on their compressive strength.