We are proud to present Volume 3 of Biological Magnetic Resonance, a series that has met with praise from the scientific community. This volume covers the new applications of various multiple irradia- tion techniques to the NMR of biomolecules; the chapter of Keller and Wuthrich describes much of the technique and its applications to hemo- proteins. The ESR of some hemoproteins in the single crystal is described by Chien and Dickinson, who also include discussions of techniques and methods for single-crystal ESR of paramagnetically intrinsic and spin- labeled protein crystals. Mims and Peisach describe the latest applications and results in electron spin echo spectroscopy of several metalloproteins. Two ESR spin probe techniques are reviewed. Chasteen describes the methods and applications of vanadyl(JV) to several systems. Ohnishi and Tokutomi describe studies of phase separations in mixed and model mem- branes by the nitroxide spin probe technique. We have been successful in continuing to provide topics that are timely and experimentally informative with a heavy emphasis on biolo- gically relevant applications. We thank our colleagues in the scientific com- munity for their suggestions on future coverage-we will remain receptive to future suggestions and comments on this series. A tentative topic list for forthcoming volumes is given on the following pages.