Wide-area damping control (WADC) has been extensively studied in recent years to suppress inter-area oscillations in power systems. This monograph summarizes the state-of-the-art on WADC design, looking at practical issues, typical off-line and adaptive WADC design methods, and engineering cases. These practical issues include design flow, mode analysis, choice of actuator and feedback, system identification and time delay. Both offline and adaptive WADC design methods are reviewed and compared. It also reviews some interesting WADC engineering cases from around the world.