Recent changes in codes and improved understanding of strong ground motions have led to increased demands in the seismic design of retaining structures. Correspondingly, the dynamic loads computed using currently available design procedures significantly exceed loads used in the design of most of the existing retaining structures, suggesting that they may have been significantly underdesigned. Field evidence from recent major earthquakes fails to show any significant problems with the performance of retaining structures designed for static earth pressures only. In view of this, an experimental and analytical study of seismic earth pressures on cantilever retaining structures was performed to address the apparent discrepancy between theory and actual performance. Two sets of dynamic centrifuge model experiments were performed to evaluate the magnitude and distribution of seismically induced lateral earth pressures on retaining structures and to study the seismic response of retaining wallbackfill systems.