The Red Book: A Deliciously Unorthodox Approach to Igniting Your Divine Spark by Sera Beak -- A really cool book about opening your mind to different types of spirituality.
The Perks of Being a Wallflower by Stephen Chbosky -- This is the single best book any outcast in high school could read.
Sarra Manning's Diary of a Crush series -- I LOVED this shit, I would recommend all of her books for young teens.
Deenie by Judy Blume -- This book is slightly lesser known than Are You There God, It's Me, Margaret? but it explores some similar themes -- puberty, masturbation, etc. but through the perspective of a girl who just found out that she has scoliosis. It appeals to that part that lives inside of every teen girl that feels like a freak.
Youth In Revolt by C.D. Payne -- I learned all about blowjobs from this book. (I know, 14 is a late bloomer. What can I say? I was sheltered.)
Girl by Blake Nelson -- An amazing book about what it's really like to try and fit in in high school.
Weetzie Bat by Francesca Lia Block -- The Weetzie Bat series chronicles a rollicking series of characters that live a totally separate reality from most teens. Thank God.
She's Come Undone by Wally Lamb -- It's a really well-written and relatable book about being an overweight teenager.
The Hunger Games --Because Katniss is the kind of girl you want to grow up to be.