This paper describes building damage functions that were developed for the FEMA/NIBS earthquake loss estimation methodology (Whitman et al., 1997). These functions estimate the probability of discrete states of structural and nonstructural building damage that are used as inputs to the estimation of building losses, including economic loss, casualties and loss of function (Kircher et al., 1997). These functions are of a new form and represent a significant step forward in the prediction of earthquake impacts. Unlike previous building damage models that are based on Modified Mercalli Intensity, the new functions use quantitative measures of ground shaking (and ground failure) and analyze model building types in a similar manner to the engineering analysis of a single structure.