The paper presents data on the taxonomic composition and naturalization features of alien plant species in the northwest of the Volga Upland. The main source of alien plants invasions is the more southern regions of Eurasia. We have identified groups of alien plants according of their invasive status as a result of an integral naturalization assessment, taking into account the following three parameters: the distribution area, ecological and cenotic confinement, and the degree of resistance in local plant communities. We have revealed the biotopic structure of the alien flora. We provide the list of plants of the Black Book of the Flora of Central Russia not previously found previously in the northwest of the Volga Upland. We present recommendations for the compilation of blacklists for the regions within the northwest of the Volga Upland.