This paper focuses on the determination of the effects on the bladed disk forced response of small variations (mistuning) in the blade-disk interface properties as may result from blade seating. A blade-interface-disk mean model is first developed that relies on both the Craig-Bampton approach and a local modeling of the interface. Then, both model and data uncertainties are introduced in this model using the nonparametric stochastic modeling approach. An example of application is presented that indicates a difference in physical behavior of a bladed disk with mistuned interfaces as compared to one with mistuned blade alone frequencies. Most notably, it is shown that at equal variability on the blade frequencies, the variations in blade-disk interface properties lead to a higher amplification factor.