Spin dynamics and the conductivity mechanism in poly(aniline) samples with different doping levels were studied by the conductometry and multifrequency EPR techniques. In the neutral polymer, the charge transport occurs predominantly through interchain transfer by hopping between pinned and mobile small polarons. A slight doping of the polymer leads to isoenergetic charge transfer between the polaron and bipolaron states according to the Kivelson theory. Ultimately high doping of poly(aniline) leads to the formation of highly conducting quasi-three dimensional clusters. In the low-temperature range, the charge transfer in these clusters proceeds by the mechanism of interchain tunneling and correlates with macromolecular librations of the polymer chain. At high temperatures, the microconductivity of the clusters is determined by the scattering of electrons on the optical lattice phonons