Radical polymerization kinetics of acenaphthylene in toluene using 2,2’-azobis(isobutyronitrile) (AIBN) as an initiator was investigated revealing an equilibrium polymerization. The values of monomer concentration at equilibrium were determined to be between 1.3 and 3.3 mol/L for a temperature range of 50-70-degrees-C. The thermodynamic parameters were determined and showed an enthalpy change of DELTAH = -43 kJ/mol and an entropy change of DELTAS = -98 J/K.mol. Furthermore, copolymerization of acenaphthylene with electron-accepting vinyl monomers such as methyl methacrylate (MMA) and acrylonitrile (AN) were carried out and showed a change from random to alternating copolymerization as the acenaphthylene concentration decreased. This change in mechanism is rationally explained in terms of the equilibrium polymerization of acenaphthylene.