4-Vinylcyclohexene reacts via the vinyl group with ethylene and propylene in a Ziegler-type polymerization to form an elastomeric terpolymer. The reactivity of vinylcyclohexene in this polymerization is lower than that of 1,4-hexadiene and norbornene by a factor of about 7 and 70, respectively. Ethylene propylene vinylcyclohexene terpolymers respond poorly to typical EPDM sulfur vulcanization systems but react well with a catalyzed resin system or a peroxide recipe.