The Definitive Guide to Boys is a hilarious and heartfelt young adult romantic comedy about first love, friendship, and the impossible science of understanding people.

Sixteen-year-old Bella Rose Richardson has spent six years creating what she believes is the ultimate solution to romance: a secret handbook called Definitive Guide to Boys. Packed with observations, statistics, compatibility charts, and ninety-nine carefully researched rules, Bella is convinced that love can be predicted, controlled, and mastered.

There's only one problem.

Every time Bella follows her own advice, everything goes wrong.

When notorious troublemaker Gian Matthews somehow gets his hands on her guidebook, Bella's carefully organized world begins to unravel. He challenges every theory she's spent years building, breaks her rules on purpose, and refuses to behave like any research subject she's ever studied. Worse, he seems determined to prove that her entire system is flawed.

As rivalries grow, secrets surface, and Bella finds herself questioning everything she thought she knew about love, she's forced to confront a terrifying possibility: What if people can't be reduced to formulas?

Perfect for fans of Jenny Han, Heartstopper, and Kaguya-sama: Love Is War, The Definitive Guide to Boys is a laugh-out-loud coming-of-age romance filled with awkward disasters, slow-burn enemies-to-lovers tension, unforgettable friendships, and the messy reality of growing up.

Because sometimes the biggest mystery isn't understanding boys.

It's understanding yourself.