The influence of three N-substituted maleimides on the thermal performance of high internal phase emulsion (HIPE) polymerized foams were investigated. N-propylmaleimide, Nbutylmaleimide, and N-cyclohexylmaleimide were copolymerized with styrene and crosslinked with either divinylbenzene or Bis(3-ethyl-5-methyl-4-maleimide-phenyl)methane in a HIPE polymerization process. All maleimide modifiers produced increases in the foam glass transition temperature (Tg) as a function of the maleimide concentration. The degree of Tg improvement was strongly dependent on the N-substituted maleimide used during processing.