Methods for evaluating the seismically induced lateral earth pressures gradually evolved from the seminal Japanese work performed in the 1920's. The resulting design procedures suggest large dynamic loads during strong ground motion. However field evidence from recent major earthquakes fails to show any significant problems with the performance of retaining structures designed for static earth pressures only. Results of a series of centrifuge experiments performed by the authors indicate that seismically induced lateral earth pressures are significantly less than those estimated using the most current design methods based on the Mononobe-Okabe assumptions. Specifically, the data show that the earth pressure distribution remains roughly triangular, increasing with depth, and the maximum dynamic moments on the retaining structure are to a large extent caused by the moment of inertia of the structures themselves. Therefore, a new approach based on direct consideration of the inertial forces due to the mass of the structure and a limited contribution by dynamic earth pressures is being proposed.