A new approach for studying high molecular weight macromolecules and macromolecular complexes is coming to the fore. Such biological systems have traditionally been very difficult to structurally characterize, because of long global correlation times, light scattering, difficulty to crystallize, and more. For biological solid state NMR these are either advantages or at the least they are not serious problems. While this spectroscopy has been around for more than two decades, due to the complexity of the instrumentation and the spectroscopy only a modest number of functional questions have been effectively studied with this approach. Now these excuses for avoiding solid state NMR are fading and exciting data relating to functional properties of macromolecules are being generated by those using the technique. Biological solid stateNMR spectroscopy has been pioneered and promoted over the years by scientists such as: Myer Bloom (Nezil and Bloom, 1992), Robert Griffin (McDermott et al., 199 1 ), Eric Oldfield (Oldfield, et al., 1991 ), Stanley Opella (Bechinger et al., 1992), and Jacob Schaefer (Marshall et al., 1990) to name a few. Many others, including Christopher Dobson (Taguchi et al., this issue) and Charles McDowell (Challoner et al., this issue) have made significant contributions to the development ofthis form ofNMR for biological studies. 'Solid state' in solid state NMR refers to the observation of nuclear sites in anisotropic environments which may