Steady-state multiplicity analysis is used to study the operability of a jacketed exothermic styrene polymerization CSTR. Low and high temperature infeasibility regions are shown to occur under certain design conditions. The approach developed is based on using a combination of analytical and numerical techniques to guide the analysis, rather than using a purely numerical approach. A reactor design used by previous researchers to show poor closed-loop performance from a single input-single output control strategy is studied in this paper. It is shown how this poor performance could have been predicted, and eliminated, at the process design stage using our bifurcation-based approach.