Solid-State Shear Pulverization (S 3 P) is a new polymer processing technology capable of efficient mixing blends with different component viscosities (which are unprocessable by conventional melt extrusion due to the phase separation). S 3 P sub ects polymers to compression and shear, resulting in fracture into a powder of various particle size and particle size distribution. S 3 P also allows modification of properties by compatibilization of ordinarily incompatible polymers without adding premade copolymers or conventional functional groups. Additionally, because S 3 P produces powder, it is suitable for a solid-state dispersion of pigments, curing agents, catalysts and other additives without melting (unlike conventional compounding). After reviewing the S 3 P concept, this paper discusses recent experimental data. The research focuses on mixing like polymers such as virgin polypropylene (PP) with unmatched viscosity, resulting in blends with improved processability and a significant increase in elongation at break. A comparison with a conventional melt mixing by twin-screw extrusion is provided to demonstrate uniqueness of S 3 P processing. An additional example involves the mixing of dissimilar, ordinarily incompatible polymers such as recycled high-density polyethylene (PE-HD), low-density polyethylene (PE-LD), PP, polystyrene (PS), and polyvinyl chloride (PVC) with very different viscosities. Once again, the S 3 P-made material exhibited exceptionally high elongation at break as compared with that of the conventionally melt-mixed blend.