Active feedforward control algorithms have proved to be successful in the attenuation of stationary disturbances such as single, multiple frequencies, and random inputs. In feedforward control, the mean square value of a measurable response quantity induced by the disturbance input is minimized by coherent ‘‘secondary’’ control inputs. The traditional design procedure is to choose the location/number of control forces and error sensors upon a physical understanding of the response of the uncontrolled and controlled systems. Thus an analytical design procedure for feedforward controlled systems is nonexistent in contrast to feedback control where pole allocation, optimal control, etc. are extensively used. Recent analytical work has demonstrated that feedforward controlled systems have new eigenproperties. The controlled eigenvalues and eigenfunctions are only functions of the control input location and the error quantity to be minimized. Here, a design methodology for feedforward controllers is presented that is based on designing an optimal error sensor such that the controlled system eigenvalues have predetermined values. The formulation is experimentally verified on a simply supported beam with an optimally shaped PVDF film sensor. [Work supported by ONR/DARPA.]