The characteristic responses of a metal deforming by continual mechanical twinning to changes in crystal orientation, temperature, strain-rate and state of order are reported. The bulk of the experiments are on single crystals of a quenched, supersaturated Fe-25 at. % Be alloy and of its ordered alternative Fe3Be. Observations on polycrystalline Fe-based alloys and single crystals of Cu, Ag and Au are also included. The most important results are a critical resolved shear stress for twinning, a positive temperature dependence of this stress, a negative strain-rate sensitivity that becomes increasingly negative at higher temperatures and an internal stress produced by the remnant twin structure after deformation that is independent of temperature. These features and others such as work hardening, twin size, and their second-order variations, are examined in terms of the formal description presented in Part I. A special contrast of the behaviors of the ordered and disordered froms of the Fe-25 Be alloy is carried throughout; this aids in the general understanding of the twinning process and serves to explain the driving force for untwinning in the ordered form.The major hypothesis of Part I, that twinning is determined by the degree of energy dissipation by slip concurrent with twinning, is indirectly corroborated by all pertinent experiments. This agreement lends support to the activation energies for slip that can be determined by using the formal description. For Ag, U ∾ 5 KT and for both Fe-25 Be and Fe3Be, U ∾ 200 kT, i.e.,12μb3. The value for Ag is consistent with observations made on slip alone; the high value for the Fe-Be alloys supports the observation that the deformation occurs primarily by twinning rather than slip.