Abstract. Ferroelectric (e.g., PZT and PMN) and ferromaqnetic (e.g., Terfenol-D) materials exhibit high energy densities, broadband drive capabilities, and the capacity for both actuating and sensing. This makes them attractive as compact transducers for applications including nanopositioning systems such as atomic force microscopes (AFM), acoustic transducers, and drive mechanisms for high speed milling. However, these materials also exhibit hysteresis and constitutive nonlinearities at all drive levels. To achieve stringent tracking requirements, it is critical to understand and quantify the effect of hysteresis and nonlinearities on the frequency behavior of devices that employ these compounds. Whereas considerable progress has been made on model development and understanding these materials in the parameter space and time domain, comprehensive quantification of these effects in the frequency domain is presently lacking. In this paper, we investigate both numerically and experimentally the effect of hystersis, constitutive nonlinearities, bias fields and AC drive levels on the frequency domain behavior of ferroelectric and ferromagnetic materials.