Abstract | This study investigates the effect of damping on the seismic demands imposed on lightweight nonstructural components. The investigation was performed utilizing a total of 113 floor acceleration recordings obtained from instrumented buildings located in California. Results are presented as damping modification factors, which provide information on the seismic demands imposed on secondary systems with various levels of damping relative to 5% damped components. Evaluations of the results indicate a strong period dependence, with the effect of damping being much larger for components that are tuned or nearly tuned and much smaller for components with periods far from the modal periods of the supporting building. Therefore, a better characterization of the effect of damping is achieved if the damping modification factors are a function of the ratio of the period of the component to the modal periods of the supporting structure. As expected, record-to-record variability increases as the level of damping in the secondary component deviates from 5% damping, with an overall probability distribution that is approximately lognormal. Thus, a full probabilistic characterization of the influence of damping on component response is offered via a parametric, period- and damping-dependent model of the mean and lognormal standard deviation of the damping modification factor.