It has been shown that in addition to classical living polymerizations, several other polymerization systems exist that may exhibit partially living so-called quasiliving character. The single requirement for quasiliving polymerization is the absence of irreversible termination. The various possible living systems have been classified by taking into consideration the absence or reversibility of termination and the absence, reversibility, or irreversibility of chain transfer. In regard to chain transfer, both unimolecular and/or bimolecular processes have been considered. A comprehensive examination of all possibilities yielded, in addition to the classical terminationless-transferless living system, five quasiliving systems. Kinetic analysis led to equations defining these systems and to diagnostic techniques useful for the classification and characterization of the mechanism of living carbocationic polymerizations.