Punctuated by pointed family discussions on attitude correction and the importance of team play, this unsubtle sibling-tiff tale should please fans of Junie B. Jones and similar whiny fare. In a mix of wordy first-person narrative and recapitulative letters to now-distant friend Mary Ann, going-on-nine Mallory details why she has her shorts in a twist over big brother Max’s new puppy Champ—her reasons centering around a loss of parental attention to her and her cat Cheeseburger. Max is no paragon of patience himself, but both (of course) ultimately come around, and Mallory even closes with a recipe for dog biscuits, plus a glimpse of the new pet scrapbook she’s making. Printed in widely spaced lines of type and illustrated with plenty of black-and-white wash cartoons, Mallory’s diatribe (her third so far) should draw, if not excite, fledgling chapter-book readers. (Fiction. 8-10)