This work deals with the model updating of two cable stayed bridges, viz, the Quincy Bayview Bridge of Illinois, USA and the Bill Emerson Memorial Bridge, Missouri, USA and studies on active response control of these bridges subjected to select seismic excitations. The finite element models for both the bridges have been updated so as to reproduce the experimentally observed modal characteristics to the closest possible extent. The control strategies for the bridges have been formulated using these updated models for development of more realistic controllers.