The article presents analysis of the influence of the 2003 electoral reform on the development of political parties in Russia’s regions. The comparative investigation realized by the author has demonstrated that the transition to the mixed electoral system at the elections to regional parliaments noticeably modified regional political actors’ strategies and gave a powerful impetus to parties’ development. It has turned out in the meantime, that it is not by regional specificity of electoral institutions that cross-regional variations in parties’ development are conditioned, but first of all by arrangement of forces on a regional political arena, and, apropos, it is not competitive, but “authoritarian” regional regimes that favour a higher level of parties’ development. According to the author’s conclusion, active party construction intensifies “vectorial differentiation” of regional political processes: authoritarian regions grow still more authoritarian, and competitive ones – still more competitive.