The use of carbon dioxide as an antisolvent for the production of polymeric particles is well documented. However, development of operating parameters to control particle size and morphology in this process has been generally lacking. In an attempt to gain a better understanding of processing conditions on particle formation, we present results on precipitation of epoxy resin powders with and without surfactants in the liquid phase including a comparison of cocurrent and countercurrent flow configurations and higher solute concentrations for increased throughput. It can be inferred from the results that for this system, mixing, nucleation, and growth phenomena in the precipitation chamber are more significant than the jet break-up effects created by the kinetic energy of the liquid solution as it is forced through the nozzle.