Jessica was the first member of what would become Girls' Generation to sign with SM Entertainment in 2000. In 2007, she was chosen as a member of the nine-member girl group that debuted on August 5, 2007. In addition to her group activities, Jessica released two singles with Seohyun and Tiffany: "Love Hate" (Korean: "오빠 나빠", lit. Bad Older Brother) and "Mabinogi (It's Fantastic!)". Jessica collaborated with 8Eight for the song "I Love You" from their second album, Infinity, which was released on March 3, 2008. Though she was the one singing the harmony and adlibs, she is not seen in the music video. In addition, she had various duets — one with Shinee member, Onew, called "One Year Later", and one with Park Myung-soo, "Naengmyeon". She sang the "Seoul Song" with Super Junior's Leeteuk, Sungmin, Donghae, Siwon, Ryeowook and Kyuhyun and fellow group members Taeyeon, Sunny, Sooyoung and Seohyun. Jessica made her musical theatre debut in the South Korean production of Legally Blonde, alongside Lee Ha-nui and Kim Ji-woo; the production opened on November 14, 2009. The same year, she took a special part on the show Infinity Challenge for their summer special, in which she was chosen to sing a duet entitled "Naengmyun" with Park Myung-soo, one of the MCs.