Lennox was inspired to write the track after seeing South African activist Zackie Achmat at Nelson Mandela's 46664 HIV/AIDS concert.

"Sing" was produced by Glen Ballard and interpolates the South African tune "Jikelele"; the music was given to Lennox by an activist group called The Generics.

She found it to be a bold statement and inquired about the man, who turned out to be Zackie Achmat, a South African activist, film director, and co-founder of the Treatment Action Campaign (TAC).

[1] Lennox was ultimately inspired to develop "Sing" based on Achmat's activism on behalf of HIV and AIDS afflicted people.

lang, Sarah McLachlan, Beth Orton, Pink, Bonnie Raitt, Shakira, Shingai Shoniwa, Joss Stone, Sugababes, KT Tunstall and, Martha Wainwright.

[6] According to Jon Pareles of The New York Times, "Sing" consists of a piano played in the background reminiscent of Marvin Gaye's 1968 single, "I Heard It Through the Grapevine".

[7] In an interview with Performing Songwriter magazine, producer Glen Ballard recalled that he completed the recording of the featured artists in various locations, conducting the sessions through the Integrated Services Digital Network (ISDN): "Shakira in Puerto Rico, Pink in Zurich, Madonna in London etc".

[4] Lennox contacted British Indian musician Nitin Sawhney to work on an alternate version of the song.

[2] Thom Jurek from AllMusic described "Sing" as a "huge feminist anthem" and described it as consisting of a "killer hook, a big bad soul/gospel refrain, and a beat that, once it gets into the spine, will not be easily dismissed".

[8] Boston Globe's Sarah Rodman compared it to the Eurythmics' 1985 single "Sisters Are Doin' It for Themselves" adding that it carried Lennox's characteristic messages of "optimism and empowerment".

[11] Similar thoughts were echoed by Chris Jones of BBC News who felt that "Sing" was able to "overcome its weighty agenda to take life as a great song in its own right".

He described it as a female point of view version of Band Aid's "Feed the World" but felt that the message got lost in the actual "gospel-tinged" composition.