This final category is even more varied in composition; composers in this list represent such divergent styles as Serialism, Minimalism, Chance or Electronic music. The primary dividing line between this classification and the preceding one is Schoenberg's usage of dodecaphonic serialism in the middle decades of this century - serial compositions are then split between the late work of Schoenberg in the previous category and the next generation of composers such as Babbitt, Boulez and Stockhausen represented here. Serial composition represents the ultimate limit of chromaticism (equal usage of the 12 notes of the chromatic scale), and as such is often difficult for the uninitiated listener to appreciate upon first hearing, though this should not be seen as a reason to avoid exposure to this music as not all listeners will react the same to any given style of music.

Serial and atonal composition gained an impressive following during the 50s and 60s, but these were not the only mode of musical expression, and have since given way to an increasingly eclectic array of styles. Most of these styles are represented in this list, many of which may be easier for the novice listener to understand. By virtue of being included in this category, it is implied that the works here are among the most approachable examples in their respective styles, and thus represent a place to start when exploring this music. However, everything in this list continues to involve substantial changes to Romantic and early 20^th century ideas on musical form.