The Year of Secret Assignments, by Jaclyn MoriartyRead about another entry on the list.
While the Ashbury-Brookfield pen pal program is designed to bring together the aforementioned boys’ and girls’ schools, the events of that momentous school year actually strengthen Cassie, Lydia, and Emily’s friendship. At first, each girl seems to have found her match in her male pen pal—new partners in crime and potential love interests. But when Cassie’s pen pal does the unimaginable, Emily and Lydia realize they’ve become too wrapped up in their correspondences to pay attention to their friend. With some help from their new pen pals, they enact the ultimate revenge plot.