The article is devoted to the point of contention between two categories in music: serious and popular. It is intended to find a solution to this musicological issue. The article contributes to the discovery and the conclusion that a crossover as a musical genre is a successful synthesis of serious and popular kinds of music and can be considered as an answer to the original question of their contrast. Some of the main musicological views on the topic are reviewed and analysed, especially Theodor Adorno and Richard Taruskin’s ones, as well as the work of a modern Russian researcher is studied in detail. Various examples of crossovers are considered and their meanings for the problematic are clarified. Keywords: serious and popular music, T. Adorno, standardization, mainstream, elitist, R. Taruskin, crossover, genre, classical crossover, I. Makalovskaya, G. Prokofiev, Ph. Glass, operatic pop, “The Three Tenors”, hit, “Barcelona”, “Pavarotti & Friends”.