Growing up in Texas, Simpson begins taking ballet lessons at age 3. "I was like twirling around when my sister had a mike in her hand," she tells Allure. At age 11, she is the youngest student ever to be accepted for a summer session at New York's prestigious School of American Ballet.
The Simpson clan moves to L.A. to develop sister Jessica's singing career. Simpson occasionally joins her sister on tour as a backup dancer. "I feel so good onstage," she tells Teen People. "It's like an out-of-body experience."
Simpson appears in her first episode of the WB family drama 7th Heaven as Cecilia Smith. Her character dates Simon (David Gallagher) and later Martin (Tyler Hoechlin). Simpson plays the role for two seasons until 2004. A few months later, she tests the movie waters with a small role in The Hot Chick alongside Rachel McAdams.
Simpson splits with boyfriend Josh Henderson, 22. "You move on," she tells PEOPLE in 2004, adding that she goes to brother-in-law Nick Lachey for guy advice. "Every time I have boyfriend trouble, he gives me the right answer: 'Make the guy jealous.' "
Simpson releases her debut song, "Just Let Me Cry" on the 2003 soundtrack for the Lindsay Lohan movie Freaky Friday. A month later, she signs a deal with Geffen to record a rock album.
The singer dyes her hair brown – and gets tons of attention for looking less like her sister. "You have one life to live. Why not have turquoise hair for two months of it?" Simpson tells PEOPLE. Jessica's best friend and stylist Ken Paves tells Entertainment Weekly, "[Going dark] is courageous and much edgier."
Simpson appears in the video for Ryan Cabrera's single "On the Way Down," playing his love interest. "I totally pulled him against the wall and started making out with him," Simpson, 19, says to Teen People of her kissing scene in the video. "That was crazy – I was shocked!" Cabrera, 21, adds. A real-life love evolves as well.
Autobiography hits No. 1 on the charts, and Simpson wins a Teen Choice Award for her first single, "Pieces of Me." Her sound is markedly different than sister Jessica's bubbly pop. "I am so proud of Jessica," Simpson tells Billboard. "But I have never listened to the kind of music that she does. We're both doing music, but in very different ways, and it's cool."
Simpson is scheduled to sing "Autobiography" on Saturday Night Live, but a recorded vocal track of "Pieces of Me" plays instead. "We all went into a state of shock," she tells MTV.com. "'Omigod, what do I do?' So I did the hoe-down and ran off." She later claims acid reflux forced her to use a prerecorded track to cover her ailing voice.
BIOGRAPHY (top to bottom): Everett; Chris Weeks/Filmmagic; Sara Jaye/Abaca; Jess Vespa/Wireimage; Lester Cohen/Wireimage; INF