An unlikely duo (a well-known writer of juvenile sf and an undergraduate at the University of Tennessee) gives us an anthology of surprising coherence. On the debit side are uninspired stories by the editors and a lot of self-congratulatory commentary about challenge, individual moral stances, active participation, and similar pieties. But the selection as a whole is intelligent: most of the thirteen stories complement each other unobtrusively, and most haven't been anthologized to death. There's an early, slightly sugary ""People"" story by Zenna Henderson, a gentle anti-regimentation fable by Asimov, a very fine early Bradbury about 21st-century pioneer women en route to Mars, and Poul Anderson's moving account of the paradoxical immortality (the result of the space-time properties of collapsing stars) conferred on the alien lover of an Earth woman. Best of anthology: Algis Budrys' ""Lower than Angels,"" an angry and uncompromising account of technology-abetted colonialism swamping both new races and human ideals. A sound collection.