I'd Tell You That I Love You, But Then I'd Have To Kill You by Ally Carter

Genre: Spy Thriller
Style: Gripping 
Recommended: 12 - 16
Other: First in six book series

This is one of the most classic and must read teen spy series. If like me you have every wished you could be a super spy then dive into the world of Gallagher Academy the secret boarding school for the most elite of young girls who are trained to be spies. If you do not read and love this book then all I can say is you do not appreciate a good novel when you find one! With this being a series of six novels you will continue to fall in love with this series with each book and no doubt be devastated when they finish. If you have every wanted to read a book about spies as well as sweet romance and tons of adventure look no further then this series. Once you've finished and if you fell in love with it as i'm sure you will then Carters other series Heist society is the perfect next series to keep you reading and falling in love with books.

Blurb:
Cammie Morgan is a student at the Gallagher Academy for Exceptional Young Women, a fairly typical all-girls school-that is, if every school taught advanced martial arts in PE and the latest in chemical warfare in science, and students received extra credit for breaking CIA codes in computer class. The Gallagher Academy might claim to be a school for geniuses but it's really a school for spies. Even though Cammie is fluent in fourteen languages and capable of killing a man in seven different ways, she has no idea what to do when she meets an ordinary boy who thinks she's an ordinary girl. Sure, she can tap his phone, hack into his computer, or track him through town with the skill of a real "pavement artist"-but can she maneuver a relationship with someone who can never know the truth about her? Cammie Morgan may be an elite spy-in-training, but in her sophomore year, she's on her most dangerous mission-falling in love.

Other books in the Gallagher Girls series:
I'd Tell You That I Love You, But Then I'd Have To Kill You (#1)
Cross My Hear And Hope To Spy (#2)
Don't Judge A Girl By Her Cover (#3)
Only The Good Spy Young (#4)
Classified Material (#4.5)
Out Of Sight, Out Of Time (#5)
Double Crossed (#5.5)
United We Spy (#6)
A Gallagher Wedding (#6.5)