Rosie Valerde is a girl that Erin and Jillian have known since the first grade. They haven't been friends with Rosie because Jilly thinks Rosie is stuck-up. Rosie, however, has the same schedule as Erin, so the two girls end up becoming friends. Rosie is of Mexican heritage, so she teaches Erin that cute boys are hot tamales. Rosie has also been friends with Mark for a very long time because their families know each other. Rosie, along with Erin and Mark, also belongs to the Intranet Club. When Erin's private website is published on the school Intranet site, Rosie is the only one that stands by Erin and tells her everything will work out.