In this thesis, the problem of singular control systems is studied in detail. Singular systems arise naturally in process control as well as other fields. Existing control algorithms are discussed and their advantages and disadvantages are compared to each other. A new method in state space is presented for state observation and disturbance attenuation. A robust control scheme for uncertain singular systems is proposed in the frequency domain in order to yield to an offset free, robust, disturbance ejective closed loop system, whose performance is superior to that of conventional state space methods. The problem of algebraic loop and its relation to the regularity concept is illustrated and an algorithm to avoid algebraic loop is proposed. The proposed method for avoiding algebraic loops is incorporated in the control system. Moreover, it is shown that the internal model control scheme for singular systems is an extension of the internal model control algorithm for standard systems. Therefore, the thesis makes an extension of the internal model control into the singular systems. Several examples were provided and the results were simulated to show the effectiveness of proposed methods.