We are pleased to present Volume 9 of our highly successful series, which now celebrates 12 years of providing the magnetic resonance community with topical, authoritative chapters on new aspects of biological magnetic resonance. As always, we try to present a diversity of topic coverage in each volume, ranging from applications of in vivo magnetic resonance to more fundamental aspects of electron spin resonance and nuclear magnetic resonance. Philip Yeagle presents an eagerly awaited chapter on 31p NMR studies of membranes and membrane protein interactions. Alan Marshall has con­ tributed two chapters to the volume: one, with Jiejun Wu, describes magnetic resonance studies of 5S-RNA as probes of its structure and conformation; the secon