Twelve reinforced masonry wall specimens with nominal dimensions of 2400 mm × 800 mm × 150 mm were tested under eccentric compressive loading with varying eccentricity to thickness ratios, e/t, and end eccentricity ratios, e₁/e₂. Pinned-pinned support conditions resulted in a slenderness ratio of 17.1 for all specimens. Test results showed that the variation of ultimate load, P_u, and effective modulus of rigidity values, EI_eff, at failure depended on the type of failure mode, which was influenced by e/t and e₁/e₂ ratios and their interaction. Comparing ultimate loads obtained by test against those calculated using the EI_eff values from the Canadian standard CSA S304.1-04 and against the ones calculated using the EI_eff values proposed herein indicates that, while the moment magnifier method used in the current Canadian design standard to account for secondary effects is effective, the standard underestimates EI_eff values, especially in regions where compression-controlled failure tends to predominate and, thus, leads to a conservative design. However, the use of proposed EI_eff values in combination with the moment magnifier method provides estimations of ultimate loads in reasonably good agreement with test results.