"It's So Hard to Say Goodbye to Yesterday" is an R&B song written by Motown husband-and-wife songwriting team Freddie Perren and Christine Yarian for the 1975 film Cooley High. In the film, the song is performed by Motown artist G.C. Cameron, whose rendition peaked at number 38 on the Billboard R&B singles chart that same year. Perren also composed the instrumental score for Cooley High, and the B-side to "It's So Hard to Say Goodbye to Yesterday" features two of his score compositions from the film.

The composition fared better when covered in an a cappella rendition by contemporary R&B Motown group Boyz II Men 16 years later. Boyz II Men's recording of "It's So Hard to Say Goodbye to Yesterday" peaked at number one on the Hot R&B/Hip-Hop Songs on December 21, 1991. Over on non-genre specific charts the song reached number five on the Hot 100 Airplay on December 7, 1991 and number two on the Hot Singles Sales on November 23, 1991 and eventually went on to peak at number two on the Billboard Hot 100 on December 14, 1991, blocked from the top spot for five weeks by Michael Jackson's single "Black or White". "It's So Hard to Say Goodbye to Yesterday" was included on Boyz II Men's first album, Cooleyhighharmony, its name a reference to the film from which the song originated.

The song was also featured in the films Lethal Weapon 3 (1992) and as the center of gags in Harold & Kumar Escape from Guantanamo Bay (2008), and in episodes of the television series It's Always Sunny in Philadelphia, Psych and Martin. It was featured in the American Dad! episode " News Glance with Genevieve VaVance" when Steve goes missing. It was also performed on Late Night with Jimmy Fallon immediately after Conan O'Brien's final Tonight Show in 2010, with Jimmy Fallon and The Roots singing it in the studio O'Brien had occupied when he hosted Late Night (now home of The Dr. Oz Show). The song was later sung by Tracy Morgan as part of a tribute to his 30 Rock co-stars that celebrated the show's then upcoming final episode. It was also featured on MTV during the current promotions of Jersey Shore's final season. In July 2013, the song was used by the show Game of Thrones at its Comic-Con panel in a tribute video to the characters killed off in its third season.

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