After the success of the last mini-album Gee, the group had a short hiatus. In late June, SM Entertainment announced that Girls’ Generation would be making a comeback with a new single and showing a "Marine Girl" concept; "Tell Me Your Wish (Genie)" was then released digitally on June 22, 2009. The group’s first performance for the mini-album was on June 26 on KBS Music Bank. Within a few days, the song topped on 10 different digital music charts. The song was also rewarded as the most popular album and ringtone downloads.

Composed by Anne Judith Wik, Robin Jenssen, Ronny Svendsen, Nermin Harambasic and Fridolin Nordso (Dsign Music), the song was originally titled "I Just Wanna Dance". After SM Entertainment had purchased the rights to the song, the lyrical story of the song was re-written with additional composition by Yoo Young-jin, and the melody arranged by Yoo Han-jin. The original song, "I Just Wanna Dance," is a song about ones lust to dance. However, in the re-worked version, the song discusses someone granting the wishes of their partner. Originally, Girls’ Generation recorded the song as "I Just Wanna Wish," and was rehearsed to by the girls, however, the song was quickly revised shortly before release, and changed to "Tell Me Your Wish (Genie)." Differences in the demo version, and the official, is most notably the presence of an ad-libbed bridge performed by Jessica, and the second chorus in which "Sowoneul Malhaebwa" ("Tell me your wish") is replaced by "I just wanna wish". As well as these, differences between this version and the Japanese version compared to the Korean version can be heard. In the Korean version, the outro features the girls playing around singing "Sowoneul Malhaebwa" whereas, in the other version, this is not heard.

"Tell Me Your Wish (Genie)" is an electropop song, with influence of eurodance. The song features a synthesized intro performed by TVXQ's Micky Yoochun, heard at the start of the Korean version, with the line, "Just turn it up, that’s right, come on!". His voice is also used in the Korean music video, with the lines "Hey" and "Girls’ Generation" being heard. The sound technique of, Musique concrète during the last chorus, in which group leader and main vocalist, Taeyeon, sings above the eight other girls – "Tell me your fantasy, without holding back. I’ll show you the genie's path. Tell me your wish, without holding back, I, your genie, will grant them." - While the other girls sing the traditional chorus.