The walls of modern low-rise economic housing in several Latin American countries are typically thin and have a low concrete strength, web steel ratios that are smaller than the minimum prescribed by current codes, and web shear reinforcement made of welded-wire mesh. In light of these particular wall characteristics, research was aimed at developing a performance-based backbone model capable of predicting the seismic behavior of reinforced concrete (RC) walls for one- and two-story housing. The selected tri-linear model is associated with three limit states: diagonal cracking, peak shear strength, and ultimate deformation capacity. The model was developed on the basis of the observed response of 39 quasi-static and shake table experiments. Iterative nonlinear regression analyses were performed for deriving the semi-empirical equations in this study. The paper also discusses the adequacy of some existing models to predict the seismic behavior of RC walls and the limitations of the proposed equations.