This thesis presents the results of an experimental study of three 1/3 to 1/2 scale model walls failing in shear under reversed cyclic loading. The main test parameter was the wall aspect ratio (height over length) . The following characteristics of response were considered: strength, displacement ductility, energy dissipation, and damageability. Recommendations are made for the design of future walls of limited ductility and the assessment of the likely seismic performance of existing walls that may respond primarily in a shear rather than flexural mode.