The effects of constraint and rate on the measured cohesive parameters are presented. The parameters were extracted from results of an experimental study of the constraint and rate-dependent fracture behavior of tough polyethylene using circumferentially notched tensile specimens described in a preceding companion paper. The study found that the cohesive parameters, the energy of separation (Gamma), the cohesive strength (sigma(peak)), and the break separation (sigma(break)) are interrelated and no single fracture parameter can be adequately used independently to describe the fracture behavior.