Following Simon and Garfunkel's split in 1970, Paul Simon transitioned to a solo career having already established himself as the duo's primary songwriter and lyricist. As the creative force behind their emotionally intelligent hits, Simon was well-positioned to succeed independently and prove that his songwriting talent extended beyond the partnership.

The track's seemingly cheerful title masks a darker emotional core. Simon discovered the phrase 'Mother and Child Reunion' on a Chinese restaurant menu, where it referred to a chicken-and-egg dish. He adopted it as his song's title after being inspired to write about the death of his pet dog, which had been struck by a car. The lyrics directly reference this tragedy, creating an unusual contrast between the song's upbeat reggae instrumentation and its sorrowful thematic content, a stylistic choice Simon later attributed to revisiting a musical approach he had previously attempted with mixed results.