We investigated the dynamic behavior of 1-3 type magnetostrictive particulate composites as a function of both bias field (5-140 kA/m) and frequency (1-100 kHz). The composites consist of approximately 0.5 volume-fraction Terfenol-D particles embedded and magnetically aligned in a passive epoxy matrix. The measured properties include elastic moduli (E3H and E3B), dynamic relative permeability (μr33), dynamic strain coefficient (d33), magnetomechanical coupling coefficient (k33), and the ratio of the dynamic strain coefficient to the dynamic susceptibility (d33/χ33). We observed the dependence of these properties on bias field and explain it here in terms of domain-wall motion followed by saturation near 40 kA/m. The spectra of μr33, d33, and d33/χ33 indicate that the magnetization process is independent of frequency and that the effect of eddy-current losses is insignificant up to 100 kHz. The observations agree with predictions made by classical eddy-current theory and suggest that the composites can be operated at significantly higher frequencies than monolithic Terfenol-D.