The elastic stresses in a multistory building due to earthquake displacements of its foundation are determined by means of the normal modes of vibration of the building and numerical integration. The building is assumed to move due to the deflection of its columns, and the mass of the structure is concentrated at the floors, which are infinitely rigid. The rocking of the building on an elastic soil and the influence of internal damping are taken into account. The stresses in the multistory building are compared with those obtained by assuming the building to act as a cantilever shear beam. A numerical example illustrates the application of the method and permits an evaluation of its accuracy and efficiency by comparison with a rigorous solution of the same problem.