For newly independent readers, a simple story (of four-and-a-half chapters) about three eight-year-old girls who live in the same apartment building; inspired by an older sister's 13th-birthday bash, they have their first sleepover. The mild events are predictable: it's not Jenny, who has the overanxious mother, who gets homesick after the scary stories, but sensible, well-organized Kate; and, despite narrator Casey's firm pronouncement that ""A person can't have two best friends,"" the three-way friendship ends up pretty close to just that. The strengths here are the well-individualized characters, their solid relationships, and the natural-sounding dialogue. Trivas's frequent full-color illustrations enhance the realism and humor; as in Ketteman's Not Yet, Yvette (below), she draws one clock carelessly--this one belies the late hour implied in the text. Still, an attractive choice for young readers who like to read about girls like themselves.