Static and dynamic coarsening and the impact of such coarsening on the plastic-flow response of Ti-6Al-4V during hot deformation at low temperatures (775, 815°C) and low-to-moderate strain rates (10^-4 – 10^-2 s^-1) were established using hot compression and hot tension tests. Program materials comprised both billet and sheet material produced via warm severe plastic deformation to obtain an ultrafine microstructure. The influence of particle size, diffusivity, alpha/beta interface energy, and phase equilibria (phase composition/volume fractions) on coarsening was established. The observed static and dynamic coarsening kinetics were both successfully interpreted in terms of models previously validated for the behavior at higher temperatures (900, 955°C). In addition, flow-hardening observations at low temperatures were analyzed in the context of the dynamic-coarsening rates. Detailed characterization studies enabled the determination of the effect of microstructural parameters/microstructure stability on plastic flow at temperatures between 775 and 955°C.