This thesis presents a flight control approach for reusable launch vehicles (RLVs). A detailed background of aerospace vehicle dynamics and control theory is provided, and the Trajectory Linearization Control (TLC) technique is presented and applied to the X-33 single-stage-to-orbit (SSTO) reusable launch vehicle. Sensitivity equations provide a method to approximate the effects that certain parameters have on the dynamic behavior of nonlinear systems. The method is used to analyze the extent to which various parameters influence the RLV flight control system. Control allocation involves the selection of vehicle actuator commands to realize commanded moments, and a dynamic control allocation (DCA) method of matching a torque impulse is presented. A test matrix is set up to test the robustness of the control methods presented for use on the X-33.