In this work we relate agglomeration in a polyethylene reactor to the solid-liquid phase transition of the polymer. The model assumes that the polyethylene dissolution temperature in the carrier [or the solid-liquid equilibrium (SLE) temperature of the polymer at the reactor conditions] correlates with, and is representative of, the onset of agglomeration in slurry reactors. We use the statistical associating fluid theory (SAFT) model for the liquid phase to study the effect of various carriers, polymer molecular weight, polymer crystallinity, and the effect of excess monomer on the SLE behavior of polyethylene. It is seen that the polyethylene-carrier SLE temperature correlates well with the onset of agglomeration for the carriers considered in this study.