The author analyzes factors that influence the efficiency of Russia’s parties’ coalition behaviour (specifying three aspects: indeterminateness, institutional design, and parties’ motivation). He comes to the conclusion, in particular, that under Russia’s conditions, a coalition’s successfulness requires proximity of ideology and, furthermore, either a leading participant, i.e. a party dominating in the «family», or, in case of no apparent leader available in the given «political family», equivalence of the parties rallied. The investigation has, then, demonstrated that electoral strategy of the parties, i.e. whether they appear at the elections jointly or separately, proves to have no impact on the success of a coalition. According to a more general conclusion contained in the article, coalition interaction in our country is now assuming the form of constructing large parties on the basis of «families of parties», with weak parties being washed away. This process, the author maintains, will result in the formation of several «monopolists» dominating their respective sectors of the parties field as a whole.