The present review is focused on the mechanistic discussion of the polymerization of multiallyl monomers including diallyl dicarboxylates, multiallyl hydroxycarboxylates, TAIC, allyl oxalates, multiallylammonium chlorides, allyl vinyl monomers, and others, based on experimental results obtained mainly in our laboratory. In particular, the inherent properties of these polymers and the mechanism for multivinyl polymerization, especially cyclopolymerization, cyclocopolymerization, and gelation are discussed in detail. Thus, anomalous head-tohead (HH) addition occurred remarkably and its chain length dependency was observed due to the steric effect of side chains. The steric effect was further re¯ected on both the cyclopolymerization of DAP and the speci®c polymerization of TAIC as a nonterminal units effect. The hydroxyl group effect was observed as an enhanced polymerizability of multiallyl hydroxycarboxylates. The polymerization of allyl oxalates was accompanied by the evolution of CO 2 at elevated temperatures. The high cyclopolymerizability and rate of polymerization were characteristic of DADMAC. The speci®c cyclopolymerization behavior of allyl maleates and fumarates was compared. Finally, monomer chain transfer, characteristic of allyl polymerization, and the re-initiation ability of the resulting allyl radicals are discussed in relation to the rate and degree of polymerization.