A versatile small‐angle x‐ray diffraction/scattering system has been developed at Stanford Synchrotron Radiation Laboratory for studies of biological and other materials. The system includes two sets of collimation slits separated by an ionization chamber, a sample holder cooled by a circulation bath, a vacuum/He scattering path after the sample holder and a detector, either a linear one‐dimensional position‐sensitive proportional counter or a position‐sensitive quadrant detector. Data aquisition is controlled by a VAXstation through a CAMAC interface. Menu‐driven data acquisition and on‐line analysis software has been developed. The system can be used to collect small‐ to intermediate‐angle x‐ray scattering and diffraction data. Monochromatic, anomalous, and time‐resolved scattering/diffraction experiments are possible. A time‐resolved spectrophotometer using photodiode arrays has also been developed for simultaneous measurements of optical absorption spectra and x‐ray scattering/diffraction.