Crazy In Love was an international #1 single from Beyoncé's debut album, Dangerously In Love. The song itself was one of the biggest songs of 2003 and spent 8 weeks atop the Billboard Hot 100 and was the first solo single from Beyoncé to reach #1. "Crazy in Love" was co-written by Beyoncé, Rich Harrison, and Jay-Z, and was co-produced by Beyoncé and Rich Harrison. It features a sample of the song "Are You My Woman (Tell Me So)", originally performed by The Chi-Lites and written by Eugene Record. The single was one of the most commercially-successful songs of 2003. The song's lyrics recall moments of temporary romantic insanity that have her "looking so crazy in love". Beyoncé states the song's hook "Looking so crazy right now" was derived from her telling her producer she shouldn't be going out looking "so crazy right now" before leaving the studio to buy former band member Kelly Rowland a birthday gift. It was a pink, fluffy envelope saying words of imaginative text messages.

Although Beyoncé had released singles as part of Destiny's Child, and had appeared as a solo artist on special soundtrack singles and guest appearances, the first single release from the Dangerously in Love album was seen as crucial in establishing her as a substantial performer in her own right; she and her record company first considered using "Naughty Girl" as the first single. While searching for a backing track, she was introduced to producer, Harrison, who produced Mary J. Blige's "Beautiful Ones", wrote and produced Kelly Rowland's "Can't Nobody", and Amerie's debut album All I Have. Harrison played a beat for her that he had created from the song "Are You My Woman (Tell Me So)". Beyoncé had to take care of some other album-related tasks, and had given Harrison only two hours to write the song. Harrison, severely hungover, was commissioned to create a melodic track for the verses and chorus he wrote. He was able to write the music for the verses and chorus in time for Beyoncé's return as she completed the song by adding the lyrics.The song was released on July 8, 2003 and recorded in Sony Music Studios in New York City.
After the completion of "Crazy in Love", record company advisors suggested to Beyoncé that she return to "Naughty Girl" as the lead single from her forthcoming album. It was believed that "Naughty Girl" would probably be a success, and a safe choice, allowing Beyoncé to convey the sexy persona that she had established with Destiny's Child; moreover, the general style, together with a well-known hook from Donna Summer's "Love to Love You Baby", was considered to be more commercial in sound than other songs Beyoncé had recorded for the album. "Crazy in Love" was seen as more of a gamble, and both the aggressive sound and attitude were somewhat different from Beyoncé's previous work.

Beyoncé insisted on moving ahead with "Crazy in Love", however, and although confident that the song was the correct choice, she felt that it might not perform well on urban charts. In order to move beyond Top 40 Mainstream markets, she enlisted her boyfriend, Jay-Z, to record a guest rap vocal performance. Like most of Jay-Z's guest raps, the verse was recorded from memory, and provided a contrast to Beyoncé's more elegant vocal style. Beyoncé hoped that the combination would allow her to move beyond Destiny's Child's reputation of pop-R&B, and as the deadline for the single's release approached, she submitted the final mixed version of the song.