Reinforced concrete walls provide effective bracing against seismic lateral loading for buildings worldwide. In Latin America, seismic design provisions commonly adhere to the ACI 318 building code, which is predominantly based on United States construction practices. However, in some Latin American countries, the construction methods and geometrical configurations of structural walls significantly differ from those in the U.S.; hence, the available information about the actual behavior of such walls under seismic loads is limited. This study focuses on a thin and lightly reinforced concrete wall (TLRCW) building system, which is characterized by walls thinner than 150 mm and primarily reinforced with a single layer of electrowelded wire steel mesh, with no boundary elements but with additional reinforcing bars at the edges. Past experiments on rectangular and T-shaped walls of the TLRCW building system, which were tested under unidirectional cyclic loading, exhibited limited rotational capacities. This article extends these findings by presenting results from a multidirectional loading test on a U-shaped thin wall and assessing its failure modes, strength and displacement capacity, deformation components, and stiffness degradation. A numerical model based on a nonlinear beam-truss approach was implemented to evaluate the accuracy of the estimates of key performance variables of the wall. The experimental results show limited displacement capacity below 1.15% drift, with a failure mode controlled by concrete crushing at the flange toes. The numerical model was able to capture some of the key global response parameters for all the load directions and at the local level, but with less accuracy. © The Author(s) 2024.