This paper presents new data and a summarization of earlier work, especially by the authors, regarding the large strain deformation (generally severe plastic deformation) of pure zirconium, generally at elevated temperatures (300-800 A degrees C range). It appears clear, now, that Zr deforms by classic five-power-law creep. Large strain deformation revealed recovery controlled mechanisms with grain refinement occurring by geometric necessary boundaries and/or the recovery-based mechanism of geometric dynamic recrystallization depending on the amount of grain elongation that occurs. No discontinuous dynamic recrystallization or grain growth was observed in the authors' tension and rolling studies. The refined ultra-fine grained substructure showed dramatically improved tensile properties over conventionally processed Zr.