Wind turbine systems present several challenging issues for control engineers charged with the design of practical controllers. The dynamics of wind turbines are essentially non-linear because of the fundamental physics governing the aerodynamic forces that drive the turbine blades and provide the means of control of the rotor. Given the more advanced dynamic modeling capability now available, more advanced control system development is underway. Such advanced controllers, will offer the significant advantage of reduced operating loads while maintaining nearly optimal energy capture. This improved control performance is likely to allow progressively larger wind turbines to economically compete with other more conventional energy production technologies.