After teaching for three years, Llewellyn came across the work of John Holt (a pioneer in youth rights theory), which led her to re-consider her approach to education. In 1991, at age 26, she wrote How to Quit School and Get a Real Life and Education.

The book concludes that education is greater than school, and aims at presenting high-school-aged teenagers with a viable alternative to the United States' compulsory school system. Llewellyn uses examples of rural and urban teenagers who choose various, alternative paths of intentional learning, and she details a variety of possible ways that teens can peruse a rich and multifaceted education and go on to attend college, without attending high school. She emphasizes using personal interests as motivation to learn in a meaningful, real-world context.

One reviewer, Jamie Littlefield, says, "Llewellyn sympathizes with teenagers who get a sub-par education, wasting hours of their time on worksheets, “classroom management,” and other needless time-busters. Instead of such waste, she contends that teens should quit school and take charge of their own learning. ...this book isn't just about lofty philosophical ideas. Llewellyn backs her claim with hundreds of pages of practical suggestions on how to claim responsibility for your educational life."

Llewellyn published the Teenage Liberation Handbook through her publishing company, Lowry House Publishers. Since its release, the book has sold tens of thousands of copies, and in 1998 it was revised and released in an international edition.

In 1996, Llewellyn started a summer camp called Not Back to School Camp, or NBTSC, attracting teens from all over the U.S., Canada, and other countries. NBTSC offers campers support in perusing varied avenues of education by connecting them with a pool of unschooling peers (about 100 other campers per session) and an eclectic staff.

Today, Llewellyn continues to direct NBTSC, and she lives in Eugene, Oregon.

Llewellyn's best known book is How to Quit School and Get a Real Life and Education (ISBN 0-9629591-7-0)

Other books include

• Guerrilla Learning: How to Give Your Kids a Real Education With or Without School (ISBN 978-0471349600) (with co-author Amy Silver) 2001
• Real Lives: Eleven Teenagers Who Don't Go to School Tell Their Own Stories (ISBN 978-0962959127) 1993, 2005
• Freedom Challenge: African American Homeschoolers (ISBN 978-0962959110) 1996