Blume might have probed this kind of opaque friendship breakup in one of her novels. But fans of schoolyard intrigue (and thus literary scandal) will be disappointed by the biography’s respectful sense of duty toward its subject. If anything, Oppenheimer can be overly besotted. “Are You There God? It’s Me, Margaret.” feels “of a moment with the confessional poetry of writers like Robert Lowell and John Berryman,” he writes. (Elsewhere, he levels about what he views as the shortcomings of Blume’s early work—“ ‘Freckle Juice’ is pleasant but inert.”) He himself has noted the incongruity of a man in his fifties serving as the biographer of the patron saint of getting your period. But his lucid, sensitive evocations of Blume’s suburban girlhood should put the question of his ability to rest. (I did laugh at his perfunctory reconstruction of Blume’s first days as a new mom: “Judy bottle-fed Randy, rocked her to sleep, changed her diapers, comforted her when she cried.”)