The Beach Boys Today! is the eighth studio album by the American rock band the Beach Boys, released March 8, 1965, by Capitol Records. Expanding on the increased musical sophistication that had marked their 1964 release All Summer Long, Today! signaled a departure from their previous work with its orchestral sound, intimate subject matter, and abandonment of car or surf songs. Side one features an uptempo sound, while side two consists mostly of introspective ballads. It has since become regarded as one of the greatest albums of all time.

The album was produced, arranged, and primarily written by Brian Wilson, with additional lyrics by Mike Love. Most of the material was recorded in January 1965 using over 25 studio musicians, following Wilson's withdrawal from touring due to a nervous breakdown. Unlike prior albums, none of the songs relied solely on traditional rock instrumentation; the arrangements incorporated timpani, harpsichord, vibraphone, French horn, and other orchestral elements, coupled with slower tempos, longer song structures, and influences drawn from Phil Spector and Burt Bacharach. Wilson also developed a more personalized, semi-autobiographical lyrical approach with recurring themes of emotional insecurity and self-doubt. The LP included "She Knows Me Too Well", depicting a man aware of his emotional cruelty; "Don't Hurt My Little Sister", in which a brother's protective stance is entangled with romantic overtones; and "In the Back of My Mind", a ballad concluding with an asynchronous instrumental collapse.

Today! reached number four in the U.S. during a 50-week chart stay and yielded three top 20 singles: "When I Grow Up (To Be a Man)" (number 9), "Dance, Dance, Dance" (number 8), and "Do You Wanna Dance?" (number 12). A rerecorded version of "Help Me, Rhonda", released in April, became the band's second U.S. number-one hit. Issued in the UK in April 1966, the album peaked at number six. The sessions also yielded the outtake "Guess I'm Dumb", a song Wilson ultimately produced for Glen Campbell. Today! contributed to the group's recognition as album artists and later the emergence of chamber/baroque pop, while retrospective commentary frequently highlights the latter half of the record as a precursor to Pet Sounds (1966).

Following the success of their chart-topping single "I Get Around", the Beach Boys undertook an intensified touring schedule. From June to August, they toured in support of their newest LP, All Summer Long, which featured their most complex arrangements to date and was their first album not centered on themes of cars or surfing. They also readied a Christmas album for release in November. By year's end, they had released four albums in 12 months and recorded the Today! singles "When I Grow Up (To Be a Man)" and "Dance, Dance, Dance". In November, they toured the UK and mainland Europe for the first time, appearing on television programs and performing live.

By this point, principal songwriter Brian Wilson had become overwhelmed by professional and personal pressures. Wilson later explained, "I used to be Mr Everything ... I was run down mentally and emotionally because I was running around, jumping on jets from one city to another on one-night stands, also producing, writing, arranging, singing, planning, teaching – to the point where I had no peace of mind and no chance to actually sit down and think or even rest." He also expressed dissatisfaction with the group's business operations and believed that the quality of their records had declined as a result. During the European tour, frontman and lyricist Mike Love told Melody Maker that the group sought to move beyond surf music and avoid repeating themselves. Asked how he felt about originating the surfing sound, Wilson rejected the label, stated that the band did not play surf music, and that their focus was a teen-oriented sound applicable to any theme: "We're just gonna stay on the life of a social teenager."

Wilson was also increasingly anxious about his relationship with singer Marilyn Rovell. During the European tour, he began drinking more heavily and turned to songwriting as an outlet. On December 7, seeking emotional stability, he married Rovell. On December 18, while en route to a U.S. tour stop in Houston, Wilson suffered a breakdown, sobbing uncontrollably during the flight. Al Jardine, seated beside him, later said, "None of us had ever witnessed something like that." Wilson performed the Houston show but was replaced by session musician Glen Campbell for the remainder of the tour. It marked the first time he had missed Beach Boys concert dates since 1963.

In the following weeks, the group resumed recording and completed the tracks for The Beach Boys Today! Wilson then informed his bandmates he would withdraw from touring indefinitely. He said, "I told them I foresee a beautiful future for the Beach Boys group, but the only way we could achieve it was if they did their job and I did mine." According to Barry Mann and Cynthia Weil, Wilson was profoundly affected by Phil Spector's latest production, "You've Lost That Lovin' Feelin'", released in November 1964. He later told a journalist that his decision to stop touring was partly due to jealousy over Spector and the Beatles. Journalist Nick Kent reported that Wilson had also been "listening intently" to the work of Burt Bacharach and Hal David.

The Beach Boys Today! marked a stylistic departure from previous Beach Boys LPs and was their most musically sophisticated to date, featuring more complex and innovative arrangements. Academic Jadey O'Regan identified it as the beginning of a period marked by unorthodox structures, "dense vocal harmonies", and eclectic orchestral textures uncommon in contemporary popular music. Musicologist Phillip Lambert rejected the notion that "Brian wrote B-side songs before his December catharsis and A-side songs in the sunny glow of his subsequent freedom", believing that the compositions which preceded his plane episode still showed evidence of progressive ingenuity.