"Endless Love" is a song written and co-produced by Lionel Richie and originally recorded as a duet between Richie and singer/actress Diana Ross for the soundtrack to the coming-of-age film of the same name, starring Brooke Shields. In this ballad, the singers declare their "endless love" for one another. It was covered by Luther Vandross with R&B-pop singer Mariah Carey, and also by country music singer Shania Twain. Billboard has named the original version as the greatest song duet of all time. It was Ross' final single with Motown Records as she would sign with RCA Records shortly before its release and Richie's first single as a solo artist prior to him leaving his longtime band, the Commodores.

Lionel Richie had been commissioned to produce the soundtrack to Franco Zeffirelli's film adaptation of Scott Spencer's novel Endless Love. Originally, Zeffirelli wanted Richie to compose an instrumental theme. Later, Zeffirelli decided the song should have lyrics and be recorded by a particular female artist, with Zeffirelli suggesting Diana Ross. Then in the last minute, Richie was told to make the song a duet, to which he volunteered to do the male lead.

At the time, Ross was struggling with negotiations to resign a new contract with Motown after becoming a free agent following the end of her previous contract with the label in November 1980, just as Ross was enjoying a commercial revival with her album, Diana. Ross had received several recording offers, including a very lucrative deal with RCA Records for $20 million. During negotiations, Ross learned from her accountants that despite recording for Motown for twenty years that she was only worth $250,000 despite several hit albums and singles for the label, during her tenure with the Supremes and as a solo artist.

Around the same time, Richie was also dealing with growing estrangement from his band, the Commodores, as Richie was often the center of attention in the group by the media, who would sometimes write articles dismissing the Commodores' funk sound and compared it to Richie's love for adult contemporary music, having penned and led on the group's number one ballads "Three Times a Lady" and "Still". Richie was later encouraged by both band mates and Motown to start his solo career.

Richie had also composed and produced Kenny Rogers' number one hit "Lady", which had originally been written for a Commodores album but was turned down by the group in protest.

Ross and Richie recorded the vocals for the song together around three in the morning at a late night recording session in Reno, where Ross had just finished a performance a couple hours earlier. According to Ross and Richie, the session went very quickly, but not smoothly.

In her 1993 memoir, Secrets of a Sparrow, Ross claimed: "I am a perfectionist. I like to be on time always. Lionel was not always on time. I did work very well, however, with the producer, James Carmichael, who is also a perfectionist."

By the time Motown decided on releasing the ballad as a single, Ross officially left the label, signing the $20 million deal with RCA. It was the most lucrative recording deal in history at the time.