The results of an experimental program designed to evaluate the influence of constituent proportions on the stress-strain relationship of Portland cement-lime mortar and grout are reported. Grout specimens consisting of 76 millimeter by 152 millimeter cylinders and mortar specimens of 50 millimeter cubes were cast and tested. Mix variations included lime and sand content. Modulus of elasticity of both mortar and grout specimens using different parts of lime and sand are presented. In addition, the relationship of the ultimate compressive strength and modulus of elasticity for various mixes is presented. Mortar cube specimens were constructed following ASTM C270, Standard Specification for Mortar for Unit Masonry. The water content used in mortar was measured as different percentages of flow of fresh mortar. Grout specimens were made in accordance with the ASTM C476, Standard Specification for Grout for Masonry. The water content was measured as different slumps of the grout. The specimens were tested at age twenty-eight days. The results define trends, resulting from varying the constituents, in the stiffness characteristics of mortar and grout.