Surface-enhanced Raman spectroscopy: Substrates and materials. This issue of MRS Bulletin highlights key field-shaping developments in surface-enhanced Raman spectroscopy (SERS) from a materials perspective. SERS is a highly sensitive vibrational spectroscopy that allows for the detection of analytes at very low concentrations. The cover shows a representation of SERS indicating molecules tucked in among gold “nanobricks.” The foreground shows transmission electron microscope images of nanoparticle clusters that were studied optically for single molecule spectroscopy. The yellow particle represents a single molecule SERS reporter occupying the interparticle gap. The arrows drawn on the nanoparticles represent excited plasmon normal modes of the clusters. The background image is courtesy of Peter Allen. See the technical theme that begins on page 607.