In this paper, the full state and output feedback controllers with gains determined using either anH2or anH8–norm optimality criterion are presented. The problem is approached by transforming the frequency domain optimality criteria to the corresponding variational forms in the time domain. The variational approach allows formulation of theH8–optimal control problem without the limitations placed by the orthogonality assumptions. The state feedback gains and the observer gains are determined by solving two special Riccati equations. The tracking and the regulation problems are presented, and a computer algorithm is proposed for determining both the controller gains and the observer gains. The theoretical developments are applied to two examples for illustrative purposes.