It is shown that interference between incident and reflected light waves at the surfaces of a transparent dielectric material significantly influences surface damage thresholds. For normal incidence the light that is reflected at the entrance face of a surface is 180° out of phase with the incident light, and the resulting interference causes a sizable reduction in the electric field at the entrance face. The light reflected at the exit face suffers no phase shift, and as a result its interference with the incident light slightly increases the electric fields experienced at the exit surface. The analysis predicts a definite ratio for the damage threshold of the entrance and exit surfaces. This and one other prediction are experimentally investigated for Owens‐Illinois ED‐2 laser glass.