The title is no hyperbole: ""Perhaps as much as ninety percent of the matter in the Universe is dark, invisible to large optical telescopes,"" say the knowing authors--Field is a Harvard astronomer and senior physicist at the Smithsonian Astrophysical Observatory, Chaisson is professor of astronomy at Haverford. Their message is that we are beginning to know what we don't know because we can fashion the right tools and techniques to see in the dark: not only have radio telescopes been sharpened and set out in huge arrays, but there is a whole body of image-enhancing computerized techniques to amplify and enrich the message picked up. Also available today are telescopes that can be placed in earth orbit or launched into space to send back data emitted in infrared, microwave, ultraviolet, x-ray, and other wavelengths along the electromagnetic spectrum. Field and Chaisson relate these instruments to particular problems posed by the astronomical community itself, in a Report commissioned by the National Academy of Sciences at the request of the federal government. The book, derived from the formal Report, naturally argues for investment in astronomical research. The authors write convincingly of the new field of astrochemistry, for example, describing research on the formation of simple compounds like ammonia in interstellar space. They also detail how new telescopes may yield information on star formation in warm compressed cloudlets, or on X-rays detected near the heart of our own galaxy that suggest proximity to a black hole. Complementing their research agenda is a short technical appendix describing the exotic tools available. Good reading for students, Popular Science readers, and NASA buffs, not to mention the astronomical community itself.