How does the mother of two coming-of-age daughters--Bronwyn, 15, and Cee-Cee, 14--relieve the communication gap where Important Issues are concerned? Well, if she's an advertising veteran like Cathy Spellman, she sits right down and writes them a letter--or two, or three. . . . Most of the entries here, unfortunately, read like Spellman had one hand on her daughters' shoulders and one eye on the potential book property: they're just too textbook-neat. And though the girls and their friends respond--quite genuinely, for the most part--to her homilies, Spellman doesn't respond to them in turn; so there's little sense of dialogue here--just disembodied voices saying their piece on sex, marriage, drugs, and more esoteric topics like good manners and patriotism. Still, for teenagers at the upper end of the reading scale (poetry ""teaches moral fortitude while showing. . . dazzling clarity of vision""), Spellman has some okay things to say and some well-researched facts to offer: from the advantages and disadvantages of various contraceptive methods, to a graphically detailed set of guidelines for staying clear of cults (if they want your mind, your money, and your exclusive presence, watch out). Spellman's a fairly modern kind of mother: she accepts and even applauds her daughters' budding sexuality, while intimating that brakes are still appropriate sometimes. But because she dares to sound authoritative, other mothers may simply make this must-reading for their daughters without using it for the discussion-catalyst it aspires to be.