Аннотация:The article covers the issue of genre heterogeneity of the 20th century American science fiction (SF). It is argued that American SF of that period was represented mainly by three subgenres: hard SF, socio-philosophical SF, and adventurous SF, that differ from each other not only in structure/content, but also in terms of genre. The novelty of the research lies in the fact that genre approach has been applied to classify American science fiction of the 20th century.