Rock in Opposition or RIO was a movement representing a collective of progressive bands in the late 1970s united in their opposition to the music industry that refused to recognise their music. It was initiated by English avant-rock group Henry Cow in March 1978 when they invited four mainland European groups to come to London and perform in a festival called "Rock in Opposition".

Progressive rock is a broad genre of rock music that primarily developed in the United Kingdom through the mid- to late 1960s, peaking in the early 1970s. Initially termed "progressive pop", the style was an emergence of psychedelic bands who abandoned standard pop traditions in favour of instrumentation and compositional techniques more frequently associated with jazz, folk, or classical music. Additional elements contributed to its "progressive" label: lyrics were more poetic, technology was harnessed for new sounds, music approached the condition of "art", and the studio, rather than the stage, became the focus of musical activity, which often involved creating music for listening rather than dancing.