In Understanding Rock: Essays in Musical Analysis, music theorist Daniel Harrison summarizes:
Even from their inception, the Beach Boys were an experimental group. They combined, as Jim Miller has put it, "the instrumental sleekness of the Ventures, the lyric sophistication of Chuck Berry, and the vocal expertise of some weird cross between the Lettermen and Frankie Lymon and the Teenagers" with lyrics whose images, idioms, and concerns were drawn from the rarefied world of the middle-class white male southern California teenager. ... [But] it was the profound vocal virtuosity of the group, coupled with the obsessional drive and compositional ambitions of their leader, Brian Wilson, that promised their survival after the eventual breaking of fad fever. ... Comparison to other vocally oriented rock groups, such as the Association, shows the Beach Boys' technique to be far superior, almost embarrassingly so. They were so confident of their ability, and of Brian's skill as a producer to enhance it, that they were unafraid of doing sophisticated, a cappella glee-club arrangements containing multiple suspensions, passing formations, complex chords, and both chromatic and enharmonic modulations.
The Beach Boys began as a garage band playing 1950s style rock and roll, reassembling styles of music such as surf to include vocal jazz harmony, which created their unique sound. In addition, they introduced their signature approach to common genres such as the pop ballad by applying harmonic or formal twists not native to rock and roll. Early on, Love sang lead vocals in the rock-oriented songs, while Carl contributed crisp guitar lines on the group's ballads. Miller observed, "On straight rockers they sang tight harmonies behind Love's lead ... on ballads, Brian played his falsetto off against lush, jazz-tinged voicings, often using (for rock) unorthodox harmonic structures." Harrison adds, "But even the least distinguished of the Beach Boys' early uptempo rock 'n' roll songs show traces of structural complexity at some level; Brian was simply too curious and experimental to leave convention alone." This new sound was quickly associated with the Modernism movement blooming in the Los Angeles music scene. Among the distinct elements of the Beach Boys' style were the nasal quality of their singing voices, their use of a falsetto harmony over a driving, locomotive-like melody, and the sudden chiming in of the whole group on a key line.
During their early years, the Beach Boys released music that displayed an increasing level of sophistication, a period where Brian Wilson consistently acted as the group's primary bandleader, songwriter, producer, and arranger for the group's most commercially and critically successful work. In a 1966 article that asks "Do the Beach Boys rely too much on sound genius Brian?" Carl responded that every member of the group contributes ideas, but admitted that Brian was majorly responsible for their music. In 1967, Dennis was cited as "the closest to brother Brian's own musical ideals ... He always emphasises the fusion, in their work, of pop and classical music." An appearance by the band on Good Morning America in 1980 was highlighted by journalist Ben Ratliff who explains: "The clip and everything about it the occasion for its happening, Dennis's shrug, Al Jardine's silence, Carl's gameness, Brian's self-absorption, Mike Love's critical stewardship of the narrative seems to say a lot, in seven minutes, about who the Beach Boys are and how they worked together."
In early 1964, Brian began his breakaway from beach-themed music. Later in November of the same year, the group expressed desires to advance from the surf rock style for which they initially became known for. New York magazine would later refer to the albums Pet Sounds and Smiley Smile as their "experimental pop phase". The band went on to incorporate many more genres, from baroque pop to psychedelia and synthpop.