A girl group is a music act featuring several female singers who generally harmonize together. The term "girl group" is also used in a narrower sense in the United States to denote the wave of American female pop music singing groups, many of whom were influenced by doo-wop and which flourished in the late 1950s and early 1960s between the decline of early rock and roll and start of the British Invasion. All-female bands, in which members also play instruments, are usually considered a separate phenomenon. These groups are sometimes called "girl bands" to differentiate, although this terminology is not universally followed.

Doo-wop is a subgenre of rhythm and blues music that originated in African-American communities during the 1940s, mainly in the large cities of the United States, including New York, Philadelphia, Pittsburgh, Chicago, Baltimore, Newark, Detroit, Washington, D.C., and Los Angeles. It features vocal group harmony that carries an engaging melodic line to a simple beat with little or no instrumentation. Lyrics are simple, usually about love, sung by a lead vocal over background vocals, and often featuring, in the bridge, a melodramatically heartfelt recitative addressed to the beloved. Harmonic singing of nonsense syllables is a common characteristic of these songs. Gaining popularity in the 1950s, doo-wop was "artistically and commercially viable" until the early 1960s and continued to influence performers in other genres.