A system and method for controlling boost pressure in various turbo-charged engine configurations as well as variable geometry turbine (VGT) arrangements includes an electronic controller programmed to receive a predetermined desired boost pressure PBoostdes. A desired pressure delta ΔPWGdes across a waste-gate valve is determined using the desired boost pressure PBoostdes. A control signal is generated for controlling the waste-gate valve so as to achieve the desired pressure delta ΔPWGdes. In boost pressure and vacuum pneumatically-actuated waste-gate valve arrangements, the respective solenoid duty cycles are obtained through use of various data structures. Where a waste-gate valve position is controlled by an electrical motor, the valve position is determined using a data structure as a function of desired waste-gate valve flow at sonic standard conditions.