Flower child originated as a synonym for hippie, especially among the idealistic young people who gathered in San Francisco and the surrounding area during the Summer of Love in 1967. It was the custom of "flower children" to wear and distribute flowers or floral-themed decorations to symbolize ideals of universal belonging, peace, and love. The mass media picked up on the term and used it to refer in a broad sense to any hippie. Flower children were also associated with the flower power political movement, which originated in ideas written by Allen Ginsberg in 1965.

The Summer of Love was a major social phenomenon that occurred in San Francisco during the summer of 1967. As many as 100,000 people, mostly young people, hippies, beatniks, and 1960s counterculture figures, converged in San Francisco's Haight-Ashbury district and Golden Gate Park. More broadly, the Summer of Love encompassed hippie culture, spiritual awakening, hallucinogenic drugs, anti-war sentiment, and free love throughout the West Coast of the United States, and as far away as New York City. An episode of the PBS documentary series American Experience referred to the Summer of Love as "the largest migration of young people in the history of America".