The moment magnifier method, used in the Canadian and American masonry design standards, is an approximate second-order analysis method based on a theoretical solution for total moments in a wall loaded by eccentric axial loads with equal end eccentricities. The ability of this procedure to account for variable load eccentricities (e1/e2), wall heights (h), eccentricity magnitude (e1), and wind load is unclear. The Canadian masonry design standard assumes the moment magnifier method adequately accounts for these variables via clauses related to lateral load magnitude and wall slenderness, which force designers to use certain values in the moment magnifier method under different conditions. The effectiveness of these clauses in parameter ranges typical of Canadian masonry wall design has not been thoroughly investigated. Thus, a numerical study was conducted on wall total moment, with walls varying in height, load eccentricity ratio and magnitude, and the presence of wind load. The study revealed that the inclusion of wind loads increased total moment values by up to 15%. The criterion for the clause to adjust the moment magnifier method for lateral loading was also not satisfied in any of the considered cases. The moment magnifier method may thus completely ignore wind loading on walls and result in substantial errors. Furthermore, the structure of the clauses intended to address slenderness and lateral load were found sometimes to improve the moment magnifier’s estimate of wall total moment, and at other times to worsen its predictions. More refined provisions appear necessary to address lateral loading in the moment magnifier method.