This report was produced as part of a research project undertaken to improve the efficiency of the jointed wall system and make the precast systems more viable for seismic regions. A new innovative and cost-effective precast system, known as the PreWEC system, was developed. Proof testing of its lateral load resisting behavior was completed through a large- scale testing of a ½-scale precast wall system at the National Center for Research on Earthquake Engineering (NCREE), Taiwan. The PreWEC test specimen (PreWEC-1) was designed to match or exceed the moment resisting capacity of the cast-in-place reinforced concrete wall with continuous longitudinal reinforcement (RWN), tested in a PreNEESR project. As part of the PreWEC testing an innovative, economical mild steel connector was developed and its behavior under cyclic shear loading was characterized using experimental and analytical means. The PreWEC system performed exceptionally well with good energy dissipation, self-centering ability, and had 15% higher capacity compared to the traditional reinforced concrete wall. A simplified analytical method was proposed to characterize the behavior and design of PreWEC systems. The method presented in this report makes similar approximation for neutral axis depth as the analytical procedure for the jointed wall systems. The simplified analysis captured an overall force-displacement response, connector displacements and wall contact length accurately. Finally, a design methodology is introduced for PreWEC systems, which is also equally applicable to single precast walls that may be designed with unbonded post-tensioning. This design methodology is similar to the guidelines proposed by ITG 5.2 for jointed wall systems. The application of this design method is also demonstrated, using design examples