p-[Bis(trimethylsilyl)methyl]isopropenylbenzene (BSIB) was prepared by reaction of alpha,p-dimethylstyrene (DMST) with lithium diisopropylamide (LDA) and trimethylsilyl chloride(TMSCl). Anionic polymerization of BSIB with sec-butyllithium (BuLi) or living lithium alpha-methylstyrene oligomers at -50-degrees-C in THF gave polymers with the predicted molecular weights and narrow molecular weight distributions. When the temperature of the polymerization mixture was increased up to 20-degrees-C after the monomer was almost completely consumed, the polymer formed disappeared almost completely, indicating the anionic polymerization of BSIB to be a living equilibrium system. The ceiling temperature of BSIB in the anionic polymerization was 1.2 +/- 0.9-degrees-C.