When her teacher, Mr. Slinger, announces he's going to marry the school nurse, Lilly—naturally—assumes she will be the flower girl. Henkes's (Lilly's Purple Plastic Purse
) black pen-and-watercolor illustrations, done in confectionary colors, show the mouse star in all her self-absorbed glory, parading across a spread, rehearsing the majestic way in which she will take the aisle. She dismisses her parents' attempt to let her down gently, and readers, too, will have caught on long before Mr. Slinger sets Lilly straight (he's already asked Ginger, his niece, to do the honors). Nonetheless, Lilly, having hinted around endlessly, is so crestfallen about Ginger's role that Mr. Slinger offers to make her the flower girl's "assistant" ("Oh, all right," Lilly deigns to accept, "if you really need me so much"). Ounce for ounce the equal in chutzpah to Falconer's Olivia, the heroine will draw laughs in nearly every scence (in one hilarious vignette, she offers "Flower Girl Advice—$1" from a makeshift stand; the audience consists of her stuffed animals). Children will identify with Lilly's intense disappointment and appreciate the way she sends a bear dressed as Mr. Slinger (with a tie and fake mustache) to the "Uncooperative Chair." There's a witty detail on every page. When Lilly finally meets the usurper, Ginger turns out to be very much in need of an assistant after all, and Lilly does what Lilly does best: she takes charge. Ages 4-up. (Apr.)