1966 proved a pivotal year in Beatles history. The band played to a wildly enthusiastic crowd at Shea Stadium in New York City, but the considerable noise from that same audience undermined the band's ability to hear each other onstage and, therefore, produce music that met their increasingly exact standards. As a consequence, the Beatles withdrew from further public performance.

Although the Beatles refrained from playing further concerts, they continued to produce successful recordings. In 1966, when they played their last concerts, they also released Revolver, which ranks among rock music's most substantial achievements. The album features McCartney on such tunes as "Eleanor Rigby," "Got to Get You into My Life, and "Here, There, and Everywhere," and it ends with Lennon singing "Tomorrow Never Knows," a radical tune with hypnotic rhythms and an instrumental interlude that includes a guitar solo played backwards. The album also contains three of Harrison's songs, including "Love You To," which indicates his interest in Indian music.

After completing Revolver, Harrison traveled to India with his wife, Patti, an actress and model who had appeared briefly in A Hard Day's Night. While in India, Harrison studied sitar with master musician Ravi Shankar, and he met with various mystics and students. Harrison's appreciation for Indian culture is evident in "Within You, Without You," which he wrote for inclusion on the Beatles' next record, Sgt. Pepper's Lonely Hearts Club Band. That 1967 album, with tunes such as the dreamy, orchestrated "A Day in the Life," has come to be recognized as a precursor to the concept album, where contents are arranged for greater song-to-song continuity. Like Revolver, Sgt. Pepper's has been hailed among the greatest recordings in rock music. John Lahr, for example, described it in The New Republic as "a majestic record in which the Beatles broke out into a whole new realm of musical sophistication." Rolling Stone reviewer Scott Isler reported that the album serves to demonstrate "that rock & roll could accommodate classical aspirations, with whatever mixed results."

With Sgt. Pepper's completed, Harrison continued to indulge himself in the music, religion, and philosophy of India. He even persuaded his band mates to share his interest, and the foursome ultimately traveled to India to practice meditation with the Maharashi Mahesh Yogi. Harrison's band mates eventually broke from the fold, but Harrison would continue to maintain an interest in Eastern culture.