Born in Milford, Pennsylvania, Carlton began playing the piano as a toddler. She went to ballet school in New York City beginning at age 12. The stress and rigid training in the ballet lessons proved too much for her, and she chose not to become a ballerina after graduating from the academy. She performed in bars and clubs all over Manhattan before launching her first album at age 21.
Carlton, along with Michelle Branch and Avril Lavigne, is often considered to have become popular in 2002 due to the alleged overexposure and insincerity of singers like Britney Spears and Christina Aguilera. While Spears and Aguilera are derided by some as oversexualized and lacking in personal creative investment in their music, singers such as Carlton are frequently considered songwriters in their own right who include more genuine sentiment in their lyrics.
Carlton's sophomore album, Harmonium, was released on November 9, 2004. The first single was "White Houses".