In late 1999, Spears appeared on the sitcom Sabrina, the Teenage Witch and performed the song "(You Drive Me) Crazy"; this cameo was a cross-promotion for the film Drive Me Crazy, which starred Sabrina's Melissa Joan Hart and was named after the song.
In December 1999, she won four Billboard Music Awards, including Female Artist of the Year. A month later, she took home the Favorite Pop/Rock New Artist award at the American Music Awards. At the 2000 Grammy Awards, Spears received two nominations in the categories of Best New Artist and Best Female Pop Vocal Performance for ...Baby One More Time, but lost to American singer Christina Aguilera and Canadian musician-singer Sarah McLachlan, respectively.
Following the success of her previous album, Spears released the album Oops!... I Did It Again. It debuted at number one in the U.S. by selling 1,319,193 units during its first week of sales, breaking the SoundScan record for the highest album sales in its debut week by any solo artist. The RIAA awarded the album with a diamond certification with 10 million copies sold in the U.S. Concerning both musical content and sales, the album was very similar to Spears's debut, although it fared better with critics. Allmusic once again gave it 4 out of 5 stars, saying that the album "has the same combination of sweetly sentimental ballads and endearingly gaudy dance-pop that made One More Time." Rolling Stone gave the album 3.5 stars out of 5 by noting the album as "fantastic pop cheese" and "Britney's demand for satisfaction is complex, fierce and downright scary."
The album's lead single of the same name broke the record for most radio station additions in a single day, and quickly became a top ten hit in the U.S. and other countries. The same year, Spears launched her first world tour, the "Oops!... I Did It Again World Tour". During the tour, she made a stop in New York for the 2000 MTV Video Music Awards. As part of her performance, she ripped off a black suit to reveal a provocative nude-colored and crystal-adorned outfit that generated much controversy. She finished the year with two more Billboard Music Awards, and two Grammy nominations for Oops!... I Did It Again in the categories of Best Pop Vocal Album and Best Female Pop Vocal Performance.