Gr 9 Up—Growing up can mean growing apart, which is a hard revelation for twins Cassie and Molly Peskin-Suso. When Cassie, who is a lesbian, begins dating Mina, a pansexual Korean American, Molly feels a little cast aside. Molly, who has an anxiety disorder, has silently nursed 26 crushes and is working on finally risking the rejection she fears and starting to date. Cassie wants Molly to hook up with Mina's best friend, Will, but Molly might be more interested in sweet and endearingly geeky Reid. While the girls are navigating these new worlds of romance, things don't slow down in other parts of their lives. Cassie and Molly's moms are finally getting married, so there's a wedding to plan, much to the delight of Pinterest-savvy Molly; plus there are jobs, friends, and a busy baby brother. Molly, Cassie, and all of the secondary characters are well-developed and distinctive. The outspoken girls have honest, humorous, and sometimes awkward conversations with each other, their friends, and their supportive and loving moms about relationships and growing up. Albertalli's keen ear for authentic teen voices will instantly make readers feel that they are a part of Cassie and Molly's world, filled with rich diversity (Cassie and Molly's family is Jewish and interracial), love, support, and a little heartache. In the satisfying conclusion, Molly and Cassie learn that letting new people into their lives does not have to mean shutting out others.