In the mid-1900s, use of lightly reinforced, perimeter walls with openings was fairly common. A large number of hospital buildings in California, constructed between 1950 and 1970, included lightly reinforced wall piers (vertical wall segments) and wall spandrels (horizontal wall segments). Therefore, accurate assessment of the as-built strength, stiffness, and deformation characteristics of lightly reinforced wall piers and spandrels could have a substantial impact on the evaluation and rehabilitation process, as well as the cost associated with the rehabilitation. Accordingly, an experimental program was conducted at UCLA on selected lightly reinforced wall pier and spandrel configurations to investigate various response attributes including shear strength, stiffness, and deformation capacity, as well as the effect of outdated construction practices such as using one curtain (vs. two) of distributed web reinforcement, discontinuity of reinforcement at a possible weakened plane joint, and the lack of hooks on transverse reinforcement, on the shear strength and lateral load behavior. Test results were compared with ACI shear strength equations and FEMA 356 lateral load vs. deformation backbone relationships to assess the reliability of these documents or the conservatism embedded therein, pertaining to seismic evaluation and rehabilitation of existing buildings. Furthermore, a comprehensive modeling approach, which incorporates flexure-shear interaction, was implemented, validated, and improved upon using test results.