The latest volume in this venerable series draws from a wide range of magazines, and the few well-known writers included (John Rolfe Gardiner, Stuart Dybek, and Lorrie Moore) are famous only by comparison to the many newcomers here. Alison Baker's ""Better Be Ready 'Bout Half Past Eight,"" which takes first prize, sets both the tone and subject for much of the collection. It's a comic account of a married man whose world is turned upside down by the news that his best friend is beginning the process of having a sex change. Contemporary sexual relations also figure in ""Not the Phil Donahue Show,"" Kelly Cherry's story of a mother dealing with her daughter's coming out of the closet; in Helen Fremont's ""Where She Was,"" a lesbian's celebration of her beloved; and in ""Semper Fidelis,"" Amy Bloom's tale of a mismatched couple. Conversely, Dybek's ""We Didn't"" is an elegy for a love unconsummated in an era of furtive sexuality. Unhappy wives, disaffected husbands, and troubled teens sleepwalk through a number of these stories. Terry Bain's ""Games"" chronicles the awkwardness of teen courtship; Elizabeth Graver's ""The Boy Who Fell Forty Feet"" finds a young boy grappling with loneliness while his father is gravely ill in the hospital; and the middle-aged mother in Elizabeth Cox's ""The Third of July"" decides not to leave her husband after witnessing a fatal car wreck on her way from home. The Vietnam War haunts no less than four stories, including David McLean's moving ""Marine Corps Issue,"" in which a son discovers his father's history as a P.O.W., and Judith Cofer's multiculturally correct tale of a Puerto Rican widow in New Jersey whose only son dies in combat (""Nada""). Second-prizewinner ""The Voyage Out,"" Gardiner's fine narrative of English schoolboys sent to Canada during WW II, reads like the beginning of an even better novel. The best piece here comes from an unlikely source, The Thoroughbred Times: In Susan Richards' flawless comic tale, ""The Hanging in the Foaling Barn,"" a small-time horse breeder talks his alcoholic nightwatchman out of suicide. Though there are a few too many clinkers, this is a welcome collection.