A new family of homogeneous polyolefin copolymers can be produced by Dow's INSITE* Technology. These ethylene/octene based, designated as polyolefin plastomers (POP) and polyolefin elastomers (POE), exhibit many unique physical and mechanical properties1,2,3,4 due to their narrow composition distribution (i.e., comonomer distribution and molecular weight distribution). In addition, the INSITE* technology also allows for the production of homogeneous copolymers with a controlled level of long chain branching (LCB) along the polymer backbone. This unique molecular structure results in many improved rheological properties5, such as enhanced shear thinning and high melt elasticity, and improved polymer melt processability6. Additionally, the unique rheological properties of the INSITE Technology polymer (ITP) also provide improved dispersion capability in rubber modified polypropylene (PP) blends. Thermoplastic polyolefins (TPO) containing ITP elastomers have excellent low temperature impact strength and injection moldability. The performance and impact toughening mechanism of the ITP impact modified PP will be discussed in this paper.