Cloud point data to 230 degrees C and 2200 bar are presented for poly(acrylate)ethylene mixtures. When the length of the alkyl tail is increased, the cloud point curve is shifted towards lower pressure, but this trend switches when going from poly(ethyl hexyl) to poly(octadecyl) acrylate. it is apparent that there is an optimum alkyl tail length that balances energetic acrylate-acrylate, ethylene-ethylene, and ethylene-acrylate interactions and free-volume, entropic effects. Both ethylene-poly(acrylate) and CO2-poly(acrylate) data are modeled by the Statistical Associating Fluid Theory (SAFT) equation of state. A pseudogroup contribution method is developed for the calculation of the following pure polymer characteristic parameters: m, the number of segments, and v(oo), the volume of a segment. This method cannot be applied for u(o)/k, the attractive energy of a segment, which changes in a nonlinear manner with changes in the structure of the acrylate repeat group. The energy parameter is then calculated from monomer data or fitted directly to one cloud point curve. The experimental data are represented well, even if little predictive power is obtained since a temperature-independent interaction parameter k(ij) is needed.