Shepard graduated from Downingtown West High School in Downingtown, Pennsylvania in 1995, and got her undergraduate degree from New York University. She later received an MFA from Brooklyn College and now lives outside Philadelphia, Pennsylvania with her husband and dogs.

Pretty Little Liars series

Shepard's bestselling Pretty Little Liars series of novels is "loosely based on her experiences growing up on Philadelphia’s Main Line." The books chronicle the exploits of four teenage girls as a mysterious stalker known as "A" threatens to reveal their darkest secrets.

1. Pretty Little Liars (October 3, 2006)
2. Flawless (March 7, 2007)
3. Perfect (August 21, 2007)
4. Unbelievable (May 27, 2008)
5. Wicked (November 25, 2008)
6. Killer (June 30, 2009)
7. Heartless (January 19, 2010)
8. Wanted (June 8, 2010)

The Visibles

Shepard's first novel for adults, The Visibles, was published on May 5, 2009. Publishers Weekly called it "tightly constructed and captivating ... complicated, rewarding and full of heart," adding that "Shepard creates a rich reading experience in shying from simple answers and happy endings."

The Lying Game'

In January 2010, Shepard announced that her next series after Pretty Little Liars would be another thriller series called The Lying Game, about twin sisters separated at birth.