We discuss the development of X-ray multilayer coatings for use as broad-band reflectors operating at energies above 100 keV. Such coatings can be used to produce hard X-ray telescopes that will make possible a variety of entirely new astronomical observations. We summarize our recent investigation into the growth, structure and hard X-ray performance of depth-graded W/Si multilayers, present follow-up information on Cu/Si multilayers, and discuss preliminary results obtained with Ni/Si, Ni._8Cr._2/Si, and Ni._(93)V._(07)/Si multilayers
