We present a cascade control strategy to treat output constraints and the switching of controls between automatic and manual in multivariable systems. The inner loop of the cascade is a multivariable IMC controller implemented in a model state feedback form so as to accommodate possible control effort saturation. The inner loop controls the output constrained variables to set points provided by the outer loop. In addition, the inner loop controls as many of the unconstrained process variables as the number of degrees of freedom allows. The outer loop adjusts the set points of the constrained variables, within their constraints, so as to: 1)achieve the set points of the unconstrained process variables, 2) drive excess controls to desired nominal values and 3) force controls which have ceased functioning due to equipment malfunction or due to being placed in manual operation., to their fixed values. Also, the outer loop may adjust unconstrained process variable set points to achieve similar objectives. A single input, two output process, and two, two input, two output processes are used to demonstrate the behavior of the new cascade constraint control algorithm. There is no performance difference between the new algorithm and the traditional override control method for the single input, two output process, with, and without, modeling errors. For the two input, two output processes, with and without deadtimes, the new algorithm successfully accommodates both control effort and process variable constraints. One control effort can be readily transferred between automatic and manual modes while maintaining control of either the output constraint, if it is active, or the unconstrained process variable, if the output constraint is not binding.