Techniques and strategies to characterize the damping properties of high-damping metals from two of the major classes of damping mechanisms are described. Two types of high-damping metals were chosen for the study: a series of die cast zinc-aluminum alloys that exhibit predominantly amplitude-independent, thermally activated damping mechanisms and a manganese-copper (Mn-Cu)-based alloy casting that exhibits pronounced amplitude-dependent damping together with thermally activated damping. It is shown that the damping behavior of the zinc-aluminum alloys can be described semi-empirically over the ranges of temperature and frequency useful in practical applications. In contrast, a similar description of the damping behavior of the Mn-Cu alloy is not possible because of the change in amplitude-dependent damping with frequency and the variation of damping with microstructural changes from place to place in the casting.