This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The SSRL SMB small-angle x-ray scattering station BL4-2 is dedicated to structural biology studies, providing state-of-the-art experimental facilities for non-crystalline diffraction and scattering studies on proteins, protein assemblies, virus particles, biological fibers and lipid membranes. The in-hutch instrumentation features a variable-distance pin-hole geometry x-ray scattering camera system, which can be configured to accommodate several data collection modes, including solution scattering, single crystal diffraction, lipid/fiber diffraction and gracing-incidence scattering. This system covers the characteristic length scale in the range of 2 A to 2000 A with seven discrete sample-to-detector distances. Advanced x-ray detectors, Rayonix MX225HE CCD and Dectris Pilatus 300K silicon pixel array detectors, are used for static and time-resolved projects, repsectively. The beam line has seen continued development of instrumentation for sample handling, in-situ monitoring of sample quality, and temperature control of sample environments.