"When You Believe" is a song from the 1998 DreamWorks musical animated feature The Prince of Egypt. It was written and composed by Stephen Schwartz. A pop single version of "When You Believe", with additional music and lyrics by writer-producer Kenneth Edmonds (Babyface), was also recorded for the film by American singers Whitney Houston and Mariah Carey for the film's end credits and its soundtrack album by DreamWorks Records. Additionally, the song serves as the soundtrack's lead single on November 2, 1998 and for both Houston's fourth studio album, My Love Is Your Love by Arista Records and Carey's first compilation album, #1's by Columbia Records. The original version of the song, featured in the narrative portion of the film, is performed by Sally Dworsky, Michelle Pfeiffer, and a children's choir (children's choir soloist: Andrew Bryan). "When You Believe" is described as a big ballad, with meaningful and inspirational lyrics, describing the ability each person has to achieve miracles when they reach out to God and believe.

The song received generally positive reviews from music critics and experienced moderate success, peaking at number 15 on the Billboard Hot 100, despite heavy media attention and live promotion. It achieved better charting throughout Europe and other nations, reaching number one in Hungary, peaking within the top five in Belgium, France, Iceland, Italy, the Netherlands, Norway, Spain, Sweden, Switzerland and the United Kingdom. "When You Believe" was awarded the Academy Award for Best Original Song at the 71st annual ceremony on March 21, 1999. Prior to their performance of the song that night, Schwartz left Babyface's name off the nomination submission sheet. He felt that because the additions Babyface added to the song were not featured in the actual film version, he did not deserve writing credits. However, while Babyface did not receive the Oscar, Carey and Houston performed his version of the song, because they were more familiar with it than the one in the film. Prior to their performance at the Academy Awards, they sang it on November 26, 1998, on The Oprah Winfrey Show, promoting the song, as well as both their albums.

The song featured two music videos. The first and most commonly seen video was filmed at Brooklyn Academy of Music performing arts center. The video features both singers, and begins with Houston and Carey performing in a large auditorium, giving the illusion of a concert. Towards the end of the video, clips of the film are projected onto a large screen at the concert, while they belt out the final verse. The alternate video was only released on NBC's special, When You Believe: Music Inspired by the Prince of Egypt, broadcast on December 13, 1998. It features a similar synopsis, with both singers performing on a large stage of an old Egyptian pyramid.