Psychedelic rock particularly took off in California's emerging music scene as groups followed the Byrds from folk to folk rock from 1965. The psychedelic life style had already developed in San Francisco and particularly prominent products of the scene were The Grateful Dead, Country Joe and the Fish, The Great Society and Jefferson Airplane. The Byrds rapidly progressed from purely folk rock in 1966 with their single "Eight Miles High", widely taken to be a reference to drug use. In Britain arguably the most influential band in the genre were The Yardbirds, who, with Jeff Beck as their guitarist, increasingly moved into psychedelic territory, adding up-tempo improvised "rave ups", Gregorian chant and world music influences to songs including "Still I'm Sad" (1965) and "Over Under Sideways Down" (1966). From 1966 the UK underground scene based in North London, supported new acts including Pink Floyd, Traffic and Soft Machine. The same year saw Donovan's folk-influenced hit album Sunshine Superman, considered one of the first psychedelic pop records, as well as the débuts of blues rock bands Cream and The Jimi Hendrix Experience, whose extended guitar-heavy jams became a key feature of psychedelia.
Psychedelic rock reached its apogee in the last years of the decade. 1967 saw the Beatles release their definitive psychedelic statement in Sgt. Pepper's Lonely Hearts Club Band, including the controversial track "Lucy in the Sky with Diamonds" and the Rolling Stones responded later that year with Their Satanic Majesties Request. Pink Floyd produced what is usually seen as their best psychedelic work The Piper at the Gates of Dawn.In America the Summer of Love was prefaced by the Human Be-In event and reached its peak at the Monterey Pop Festival, the latter helping to make major American stars of Jimi Hendrix and The Who, whose single "I Can See for Miles" delved into psychedelic territory. Key recordings included Jefferson Airplane's Surrealistic Pillow and The Doors' Strange Days. These trends climaxed in the 1969 Woodstock festival, which saw performances by most of the major psychedelic acts, but by the end of the decade psychedelic rock was in retreat. Brian Wilson of the Beach Boys, Brian Jones of the Rolling Stones, Peter Green of Fleetwood Mac andSyd Barrett of Pink Floyd were early "acid casualties", the Jimi Hendrix Experience and Cream broke up before the end of the decade and many surviving acts moved away from psychedelia into more back-to-basics "roots rock", the wider experimentation of progressive rock, or riff laden heavy rock.