Base isolation is a strategy that is effective in mitigating the effects of earthquakes in certain structures. Interest in base isolation is developing worldwide and research results are beginning to become available for translation into engineering practice. This research project will study combining concepts of base isolation with those of active control to mitigate the effects of earthquakes. The research will consist of developing active control strategies, numerically simulating structural response, studying effects of delayed information, and performing preliminary experimenttion. The results will provide a determination of feasibilty of using this combined concept for earthquake hazard mitgation in structures.