Like Judy Blume, Klein has written for both the YA and adult fiction markets, and her simulated teen talk (much less tangy and perspicacious than Blume's) glides along as if on automatic prlot, targeting here Big Teen Topics like too-young marriage and tolerance of incomprehensible oldsters. There's even a boy's-eye view of women's lib. But the pseudo revelations land with only a light ping. Eighteen-year-old Spencer Searles, earnestly plowing through his last summer before entering the University of Michigan, does part-time carpentry and good works. Good works are in the form of a weekly donation of sperm to the Michigan Repository for Germinal Choice, a sperm bank for women in need of an anonymous partner in conception. Raised by grandparents (and four older sisters) orphaned Spence has the urge to help women. The only other male in the family is Grandfather Omar, a sour apple, quick on the insult trigger, on whom doting Grandmother waits upon hand and foot. Then there's Taffy, a former classmate miserably married to Spence's pal Linc. The marriage is a bummer, and their baby's a pain. But Audrey Rummel, the twenty-year-old divorced travel agent's clerk, is different. She wants to be an airline pilot, and even is really understanding when Spence tells her he's saving himself for the sperm bank. But not for long. Sex with Audrey, who really likes him and his whole body, is fantastic. However, sex with Taffy, a Spence groupie who just won't keep away, is crazy--guilt, guilt guilt. Troubles pile up. Grandfather has died, and Grandmother settles his photo in a chair, drapes a shawl around it, and carries on conversations with the departed. In the end, Audrey blinks out of Spence's life and it's awful, and Taffy goes bananas, but Spence makes it to college anyway and stays away from women--for a while. Spence, through his mini-cogitations, is rather a dim bulb, but then, he's surrounded by some dippy others, left free-floating and unplumbed, either for humor or depths. Teen troubles--muddled and meandering, but confessional gab re the tremors surrounding Doing It has a built-in YA appeal.