Despite widespread and growing use of polymers in applications where abrasion is present, ranging from gearboxes to prosthetic joints, abrasive wear of these materials is ill-understood. We present a study that for commercially relevant polyethylene (PE) points to the effective number of physical cross-links per macromolecular chain as the principal-remarkably simple-factor that dictates the intrinsic abrasive wear resistance. This new insight has permitted us, among other things, to identify a polyethylene of a hereto unknown matrix of desirable properties, i.e., ultra-wear-resistant and-unlike the commonly used ultrahigh molecular weight version (UHMW PE)-melt-processable, which should open a host of novel applications.